Income Tax Disclosure [Abstract] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Balance, beginning of year Unrecognized Tax Benefits Gross increases — tax positions related to prior years Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Gross decreases — tax positions related to prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Lapse of statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Balance, end of year Business Combinations [Abstract] Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table] Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] StarStone StarStone Insurance Bermuda Limited [Member] StarStone Insurance Bermuda Limited [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Technology Developed Technology Rights [Member] Brand Brand [Member] Brand [Member] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Syndicate capacity Syndicate Capacity [Member] Syndicate Capacity [Member] U.S. insurance licenses Us Insurance Licenses [Member] Us Insurance Licenses [Member] Acquired Finite-Lived Intangible Assets [Line Items] Acquired Finite-Lived Intangible Assets [Line Items] Intangible assets as of the acquisition date, indefinite-lived Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets Intangible assets as of the acquisition date, finite-lived Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Intangible assets as of the acquisition date Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Intangible assets as of the acquisition date, economic useful life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Commitments and Contingencies Disclosure [Abstract] 2017 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2018 Operating Leases, Future Minimum Payments, Due in Two Years 2019 Operating Leases, Future Minimum Payments, Due in Three Years 2020 Operating Leases, Future Minimum Payments, Due in Four Years 2021 Operating Leases, Future Minimum Payments, Due in Five Years 2022 and beyond Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table] Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table] Sussex Insurance Company, National Suisse Assurance S.A., and Wilton Relife Settlements Sussex Insurance Company, National Suisse Assurance S.A., and Wilton Re Limited [Member] Sussex Insurance Company, National Suisse Assurance S.A., and Wilton Re Limited [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Sussex Insurance Company Sussex Insurance Company [Member] Sussex Insurance Company [Member] Alpha Nationale Suisse Assurance Sa [Member] Nationale Suisse Assurance Sa [Member] Wilton Re Wilton Re Limited [Member] Wilton Re Limited [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Pro forma Pro Forma [Member] Nonrecurring Adjustment [Axis] Nonrecurring Adjustment [Axis] Nonrecurring Adjustment [Domain] Nonrecurring Adjustment [Domain] Income adjustment Revenues Adjustment [Member] Revenues Adjustment [Member] Expense adjustment Expenses Adjustment [Member] Expenses Adjustment [Member] Noncontrolling interest adjustment Net Income (Loss) Attributable To Noncontrolling Interest Adjustment [Member] Net Income (Loss) Attributable To Noncontrolling Interest Adjustment [Member] Net earnings (loss) adjustment Net Income (Loss) Adjustment [Member] Net Income (Loss) Adjustment [Member] Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] Total income Revenues Total expenses Benefits Losses And Expenses And Income Tax Expense (Benefit) Benefits Losses And Expenses And Income Tax Expense (Benefit) Total noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest NET EARNINGS ATTRIBUTABLE TO ENSTAR GROUP LIMITED Net Income (Loss) Attributable to Parent Business Acquisition, Pro Forma Information [Abstract] Business Acquisition, Pro Forma Information [Abstract] Total income Business Acquisition, Pro Forma Revenue Total expenses Business Acquisitions, Pro Forma Expenses Business Acquisition, Pro Forma Expenses Total noncontrolling interest Business Acquisition, Pro Forma Net Income (Loss) Attributable To Noncontrolling Interest Business Acquisition, Pro Forma Net Income (Loss) Attributable To Noncontrolling Interest Net earnings (loss) Business Acquisition, Pro Forma Net Income (Loss) Noncontrolling Interest [Abstract] Carrying Amount of Equity Attributable to Noncontrolling Interest Redeemable Noncontrolling Interest [Table Text Block] Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Recurring Fair Value, Measurements, Recurring [Member] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Other Investments Other Investments [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Other investments measured at fair value Investments, Excluding Net Asset Value, Fair Value Disclosure Investments, Excluding Net Asset Value, Fair Value Disclosure Other investments measured at NAV as practical expedient Alternative Investments, Fair Value Disclosure Total other investments shown on balance sheets Investments, Fair Value Disclosure Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Goodwill and Intangible Assets Schedule of Goodwill, Intangible Assets, Intangible Assets Arising from Insurance Contracts Acquired in Business Combination, and Deferred Charges Disclosure [Table Text Block] Schedule of Goodwill, Intangible Assets, Intangible Assets Arising from Insurance Contracts Acquired in Business Combination, and Deferred Charges Disclosure [Table Text Block] Summary of Estimated Amortization Expense of Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Debt Disclosure [Abstract] Amounts of Loans Payable Outstanding, and Accrued Interest Schedule of Long-term Debt Instruments [Table Text Block] Earnings before income tax Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Bermuda income taxes at statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Foreign income tax rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent Change in unrecognized tax benefits Effective Income Tax Rate Reconciliation, Tax Settlement, Percent Benefit of loss carryovers Effective Income Tax Rate Reconciliation Benefit Of Operating Loss Carryforward Effective Income Tax Rate Reconciliation Benefit Of Operating Loss Carryforward Change in valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Investment write-off Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Percent Foreign currency translation Effective Income Tax Rate Reconciliation Foreign Currency Translation Effective Income Tax Rate Reconciliation Foreign Currency Translation Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Effective tax rate Effective Income Tax Rate Reconciliation, Percent Supplemental Information for Property, Casualty Insurance Underwriters [Abstract] Schedule VI - Supplementary Information Concerning Property/Casualty Insurance Operations Schedule of Supplemental Information for Property, Casualty Insurance Underwriters [Text Block] Investments, Debt and Equity Securities [Abstract] Other than temporary impairment losses, available-for-sale securities Other than Temporary Impairment Losses, Investments, Available-for-sale Securities Schedule of Other than Temporary Impairment, Credit Losses Recognized in Earnings [Table] Schedule of Other than Temporary Impairment, Credit Losses Recognized in Earnings [Table] Debt Security Category [Axis] Debt Security Category [Axis] Other than Temporary Impairment, Credit Losses Recognized in Earnings, Categories of Investments [Domain] Other than Temporary Impairment, Credit Losses Recognized in Earnings, Categories of Investments [Domain] Available-for-sale securities Available-for-sale Securities [Member] Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] Credit losses Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held Insurance [Abstract] Short-duration Insurance Contracts, Historical Claims Duration [Table] Short-duration Insurance Contracts, Historical Claims Duration [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Non-life Run-off Non-Life Run-Off Segment [Member] Non-Life Run-Off Company Segment [Member] Atrium Atrium Segment [Member] Atrium Segment [Member] StarStone StarStone Segment [Member] StarStone Segment [Member] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] General casualty General Casualty Insurance Product Line [Member] General Casualty Insurance Product Line [Member] Workers' compensation Workers Compensation Insurance Product Line [Member] Workers Compensation Insurance Product Line [Member] Short-duration Insurance Contracts, Historical Claims Duration [Line Items] Short-duration Insurance Contracts, Historical Claims Duration [Line Items] Year 1 Short-duration Insurance Contracts, Historical Claims Duration, Year One Year 2 Short-duration Insurance Contracts, Historical Claims Duration, Year Two Year 3 Short-duration Insurance Contracts, Historical Claims Duration, Year Three Year 4 Short-duration Insurance Contracts, Historical Claims Duration, Year Four Year 5 Short-duration Insurance Contracts, Historical Claims Duration, Year Five Year 6 Short-duration Insurance Contracts, Historical Claims Duration, Year Six Year 7 Short-duration Insurance Contracts, Historical Claims Duration, Year Seven Year 8 Short-duration Insurance Contracts, Historical Claims Duration, Year Eight Year 9 Short-duration Insurance Contracts, Historical Claims Duration, Year Nine Year 10 Short-duration Insurance Contracts, Historical Claims Duration, Year Ten Accounting Policies [Abstract] Number of types of compensation Share Based Compensation, Number of Types of Compensation Share Based Compensation, Number of Types of Compensation Segment Reporting [Abstract] Reconciliation of Assets from Segment to Consolidated [Table] Reconciliation of Assets from Segment to Consolidated [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Eliminations Intersegment Eliminations [Member] Life and annuities Life and Annuities Segment [Member] Life and Annuities Segment [Member] Segment Reporting, Asset Reconciling Item [Line Items] Segment Reporting, Asset Reconciling Item [Line Items] Total assets Assets Policy Benefits for Life Contracts Liability for Future Policy Benefits and Unpaid Claims Disclosure [Text Block] Significant Accounting Policies Significant Accounting Policies [Text Block] Schedule of Funds Held, Directly Managed [Table] Schedule of Funds Held, Directly Managed [Table] Schedule of Funds Held, Directly Managed [Table] Funds held – directly managed Funds Held - Directly Managed [Member] Funds Held - Directly Managed [Member] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] U.S. government and agency US Government Agencies Debt Securities [Member] Non-U.S. government Foreign Government Debt Securities [Member] Corporate Corporate Debt Securities [Member] Municipal Municipal Bonds [Member] Commercial mortgage-backed Commercial Mortgage Backed Securities [Member] Asset-backed Asset-backed Securities [Member] Schedule of Funds Held, Directly Managed [Line Items] Schedule of Funds Held, Directly Managed [Line Items] [Line Items] for Schedule of Funds Held, Directly Managed [Table] Trading securities, debt Trading Securities, Debt Funds held - directly managed, other assets Funds Held, Directly Managed, Other Assets Funds Held, Directly Managed, Other Assets Funds held - directly managed Funds Held under Reinsurance Agreements, Directly Managed, Net Asset Funds Held under Reinsurance Agreements, Directly Managed, Net Asset Supplementary Insurance Information [Abstract] Schedule III - Supplementary Insurance Information Supplementary Insurance Information, for Insurance Companies Disclosure [Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative [Table] Derivative [Table] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Foreign Exchange Forward Foreign Exchange Forward [Member] Equity Option Equity Option [Member] Currency [Axis] Currency [Axis] All Currencies [Domain] All Currencies [Domain] Canada, Dollars Canada, Dollars Australia, Dollars Australia, Dollars Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] EGL Revolving Credit Facility EGL Revolving Credit Facility [Member] EGL revolving credit facility. Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Loan facilities Line of Credit [Member] Derivative [Line Items] Derivative [Line Items] Number of derivative contracts Derivative, Number of Instruments Held Gross Notional Amount Derivative, Notional Amount Assets Derivative Asset Liabilities Derivative Liability Amount of Gains Deferred in AOCI (Effective Portion) Gain (Loss) on Derivative Used in Net Investment Hedge, Net of Tax Proceeds from line of credit Proceeds from Long-term Lines of Credit Cost Derivative Asset, Notional Amount Realized gain Gain (Loss) on Sale of Derivatives Deferred Acquisition Costs Supplemental Information for Property, Casualty Insurance Underwriters, Deferred Policy Acquisition Costs Reserves for Unpaid Losses and Loss Adjustment Expenses Supplemental Information for Property, Casualty Insurance Underwriters, Reserves for Unpaid Claims and Claims Adjustment Expense Unearned Premiums Supplemental Information for Property, Casualty Insurance Underwriters, Unearned Premiums Net Premiums Earned Supplemental Information for Property, Casualty Insurance Underwriters, Earned Premiums Net Investment Income Supplemental Information for Property, Casualty Insurance Underwriters, Net Investment Income Net Losses and Loss Expenses Incurred - Current Year Current Year Claims and Claims Adjustment Expense Net Loses and Loss Expenses Incurred - Prior Year Prior Year Claims and Claims Adjustment Expense Net Paid Losses and Loss Expenses Supplemental Information for Property, Casualty Insurance Underwriters, Paid Claims and Claims Adjustment Expense Amortization of Deferred Acquisition Costs Supplemental Information for Property, Casualty Insurance Underwriters, Amortization of Deferred Policy Acquisition Costs Net Premiums Written Supplemental Information for Property, Casualty Insurance Underwriters, Premiums Written Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] KaylaRe KaylaRe Holdings Ltd [Member] KaylaRe Holdings Ltd. [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Equity method investee Equity Method Investee [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Starstone Starstone [Member] Starstone [Member] Subsidiaries Subsidiaries [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Initial capital raise Proceeds from Issuance or Sale of Equity Equity method investment ownership percentage Equity Method Investment, Ownership Percentage Warrants to purchase common shares, up to (shares) Class of Warrant or Right, Number of Securities Called by Warrants or Rights Warrants, exercise price (dollars per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Equity method investment Equity Method Investments Shareholders Agreement, right to appoint board members, number of members Shareholders Agreement, Right To Appoint Members To Board of Directors, Number of Members Shareholders Agreement, Right To Appoint Members To Board of Directors, Number of Members Shareholders Agreement, minimum number of shares owned for right to appoint board members Shareholders Agreement, Minimum Number of Common Shares Owned For Right To Appoint Board Members Shareholders Agreement, Minimum Number of Common Shares Owned For Right To Appoint Board Members Shareholders Agreement, lock-up period on common shares Shareholders Agreement, Lock-Up Period On Common Shares Shareholders Agreement, Lock-Up Period On Common Shares Percentage reinsured of certain businesses Percentage of Business Reinsured Percentage of Business Reinsured Ceded, premiums earned Ceded Premiums Earned Net incurred losses and LAE Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Acquisition costs Business Combination, Acquisition Related Costs Ceded reinsurance receivables Ceded Reinsurance Receivables Ceded Reinsurance Receivables Reinsurance recoverable Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments Ceded unearned premium Unearned Premiums, Ceded Unearned Premiums, Ceded Funds held Funds Held under Reinsurance Agreements, Liability Reinsurance balances payable Reinsurance Payable Ceded acquisition costs Deferred Policy Acquisition Costs, Ceded Deferred Policy Acquisition Costs, Ceded Effects of Reinsurance [Table] Effects of Reinsurance [Table] Effects of Reinsurance [Line Items] Effects of Reinsurance [Line Items] Outstanding losses Reinsurance Recoverable for Unpaid Claims and Claims Adjustments, Excluding Incurred But Not Reported Reinsurance Recoverable for Unpaid Claims and Claims Adjustments, Excluding Incurred But Not Reported IBNR Reinsurance Recoverables, Incurred but Not Reported Claims Fair value adjustments Reinsurance Recoverable, Fair Value Adjustment Amount of addition (reduction) at which reinsurance recoverable could be incurred (settled) in a current transaction between willing parties. Total reinsurance reserves recoverable Reinsurance Recoverable, Before Paid Claims Reinsurance Recoverable, Before Paid Claims Paid losses recoverable Reinsurance Recoverable for Paid Claims and Claims Adjustments Net Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Dana Companies Dana Companies, LLC [Member] Dana Companies, LLC [Member] Nationale Suisse Assurance S.A. Business Acquisition [Line Items] Business Acquisition [Line Items] Purchase price Business Combination, Consideration Transferred Net assets acquired at fair value Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Excess of purchase price over fair value of net assets acquired Goodwill Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] 2017 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2018 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Five Investment Income [Table] Investment Income [Table] Fixed maturities Fixed Maturities [Member] Short-term investments and cash and cash equivalents Short Term Investments And Cash Equivalents [Member] Short Term Investments And Cash Equivalents [Member] Net Investment Income [Line Items] Net Investment Income [Line Items] Investment income on funds held - directly managed Net Investment Income Equity [Abstract] Share Capital Stockholders' Equity Note Disclosure [Text Block] Carrying Values of Assets and Liabilities Underlying Funds Held - Directly Managed Funds Held, Directly Managed, Carrying Values of Assets [Table Text Block] Funds Held, Directly Managed, Carrying Values of Assets [Table Text Block] Contractual Maturities of Fixed Maturity Investments Underlying Funds Held - Directly Managed Funds Held, Directly Managed, Classified by Contractual Maturity Date [Table Text Block] Funds Held, Directly Managed, Classified by Contractual Maturity Date [Table Text Block] Funds Held - Directly Managed, by Credit Rating Schedule of Funds Held, Directly Managed, by Credit Rating [Table Text Block] Schedule of Funds Held, Directly Managed, by Credit Rating [Table Text Block] Net Realized and Unrealized Investment (Losses) Gains Funds Held, Directly Managed, Realized and Unrealized Gains and Losses [Table Text Block] Funds Held, Directly Managed, Realized and Unrealized Gains and Losses [Table Text Block] Net Investment Income Funds Held, Directly Managed, Investment Income [Table Text Block] Funds Held, Directly Managed, Investment Income [Table Text Block] Compensation and Retirement Disclosure [Abstract] Share-Based Compensation and Pensions Compensation and Employee Benefit Plans [Text Block] Trading Securities [Table] Trading Securities [Table] Residential mortgage-backed Residential Mortgage Backed Securities [Member] Commercial mortgage-backed Schedule of Trading Securities and Other Trading Assets [Line Items] Schedule of Trading Securities and Other Trading Assets [Line Items] Amortized Cost Trading Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract] Trading Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract] One year or less Trading Securities, Debt Maturities, Next Rolling Twelve Months, Amortized Cost Trading securities debt maturities within one year amortized cost. More than one year through two years Trading Securities, Debt Maturities, Rolling Year Two, Amortized Cost Trading securities debt maturities after one through two years amortized cost. More than two years through five years Trading Securities, Debt Maturities, Rolling Year Three Through Five, Amortized Cost Trading securities debt maturities after two years through five years amortized cost. More than five years through ten years Trading Securities, Debt Maturities, Rolling Year Six Through Ten, Amortized Cost Trading Securities, Debt Maturities, Rolling Year Six Through Ten, Amortized Cost More than ten years Trading Securities, Debt Maturities, Rolling after Ten Years, Amortized Cost Trading securities debt maturities after ten years amortized cost. Securities without single maturity date Trading Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis Trading Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis Trading securities, amortized cost Trading Securities, Debt, Amortized Cost Fair Value Trading Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract] Trading Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract] One year or less Trading Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value Trading Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value More than one year through two years Trading Securities, Debt Maturities, Rolling Year Two, Fair Value Trading securities debt maturities after one through two years fair value. More than two years through five years Trading Securities, Debt Maturities, Rolling Year Three Through Five, Fair Value Trading securities debt maturities after two years through five years fair value. More than five years through ten years Trading Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value Trading securities debt maturities after five years through ten years fair value. More than ten years Trading Securities, Debt Maturities, Rolling after Ten Years, Fair Value Trading securities debt maturities after ten years fair value. Securities without single maturity date Trading Securities, Debt Maturities, without Single Maturity Date, Fair Value Trading Securities, Debt Maturities, without Single Maturity Date, Fair Value Trading securities, debt % of Total Fair Value Trading Securities, Debt Maturities, Percent of Total Fair Value, Rolling Maturity [Abstract] Trading Securities, Debt Maturities, Percent of Total Fair Value, Rolling Maturity [Abstract] One year or less Trading Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value, Percent Trading securities debt maturities within one year percent of fair value. More than one year through two years Trading Securities, Debt Maturities, Rolling Year Two, Fair Value, Percent Trading securities debt maturities after one year through two years percent fair value. More than two years through five years Trading Securities, Debt Maturities, Rolling Year Three Through Five, Fair Value, Percent Trading securities debt maturities after two years through five years percent of fair value. More than five years through ten years Trading Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value, Percent Trading securities debt maturities five years through ten years percent of fair value. More than ten years Trading Securities, Debt Maturities, Rolling after Ten Years, Fair Value, Percent Trading securities debt maturities after ten years percent of fair value. Securities without single maturity date Trading Securities, Debt Maturities, without Single Maturity Date, Fair Value, Percent Trading securities percentage of fair value. Trading securities, percentage of fair value Trading Securities, Percentage Of Fair Value Trading Securities, Percentage Of Fair Value Equity securities Equity Securities [Member] Mortgage-backed Securities, Issued by US Government Sponsored Enterprises Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Senior Secured Debt Securities Senior Secured Debt Securities [Member] Senior Secured Debt Securities [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] US UNITED STATES International Non-US [Member] Equities, trading, at fair value Trading Securities, Equity Trading securities Trading Securities Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Debt Security [Axis] Debt Security [Axis] Major Types of Debt Securities [Domain] Major Types of Debt Securities [Domain] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Transfers between Levels 2 and 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Transfers between Levels 3 and 2 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Abstract] Reinsurance Premiums for Insurance Companies, by Product Segment [Table] Reinsurance Premiums for Insurance Companies, by Product Segment [Table] Property and casualty Property, Liability and Casualty Insurance Product Line [Member] Life and annuities Life and Annuity Insurance Product Line [Member] Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items] Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items] Life insurance in force, gross Life Insurance in Force, Gross Life insurance in force, ceded Life Insurance in Force, Ceded Life insurance in force, assumed Life Insurance in Force, Assumed Life insurance in force, net Life Insurance in Force, Net Life insurance in force, percentage of amount assumed to net Life Insurance in Force, Percentage Assumed to Net Premiums earned, gross Direct Premiums Earned Premiums earned, ceded Premiums earned, assumed Assumed Premiums Earned Net, premiums earned Premiums Earned, Net Premiums earned, percentage of amount assumed to net Premiums, Percentage Assumed to Net Organization, Consolidation and Presentation of Financial Statements [Abstract] Description of Business Nature of Operations [Text Block] Supplementary Insurance Information, by Segment [Table] Supplementary Insurance Information, by Segment [Table] Supplementary Insurance Information, by Segment [Line Items] Supplementary Insurance Information, by Segment [Line Items] Deferred Acquisition Costs Supplementary Insurance Information, Deferred Policy Acquisition Costs Reserves for Losses and Loss Adjustment Expenses Supplementary Insurance Information, Losses, Claims and Loss Expense Reserves Supplementary Insurance Information, Losses, Claims and Loss Expense Reserves Unearned Premiums Supplementary Insurance Information, Unearned Premiums Policy Benefits for Life and Annuity Contracts Supplementary Insurance Information, Liability for Future Policy Benefits Supplementary Insurance Information, Liability for Future Policy Benefits Net Premiums Earned Supplementary Insurance Information, Premium Revenue Net Investment Income Supplementary Insurance Information, Net Investment Income Losses and Loss Expenses and Policy Benefits Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense Amortization of Deferred Acquisition Costs Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs Other Operating Expenses Supplementary Insurance Information, Other Operating Expense Net Premiums Written Supplementary Insurance Information, Premiums Written Loss contingency accrual Loss Contingency Accrual Accrual for environmental liabilities Accrual for Environmental Loss Contingencies Insurance recoveries receivable Loss Contingency, Receivable Rent expense Operating Leases, Rent Expense Commitments, unfunded Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Concentration Risk [Table] Concentration Risk [Table] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Reinsurer concentration risk Reinsurer Concentration Risk [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Reinsurance balances recoverable Reinsurance Recoverable [Member] Concentration Risk [Line Items] Concentration Risk [Line Items] Funds held by reinsured companies Funds Held under Reinsurance Agreements, Asset Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Limited parental guarantee Limited Parental Guarantee [Member] Limited Parental Guarantee [Member] Guarantor Obligations [Line Items] Guarantor Obligations [Line Items] Total parental guarantees Guarantor Obligations, Current Carrying Value Collateral for line of credit facility Funds in Syndicate, Collateral for Line of Credit Facility Funds in Syndicate, Collateral for Line of Credit Facility Condensed Financial Information of Parent Company Only Disclosure [Abstract] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Enstar Group Limited Parent Company [Member] Condensed Cash Flow Statements, Captions [Line Items] Condensed Cash Flow Statements, Captions [Line Items] OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net cash flows provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Dividends and return of capital from subsidiaries Cash Dividends Paid to Parent Company Contributions to subsidiaries Payments to Subsidiaries Payments to Subsidiaries Net cash flows provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Repayment of loans Repayments of Long-term Debt Receipt of loans Proceeds from Issuance of Long-term Debt Net cash flows provided by financing activities Net Cash Provided by (Used in) Financing Activities NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH Cash and Cash Equivalents, Period Increase (Decrease) CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF YEAR Cash and Cash Equivalents, at Carrying Value CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF YEAR INCOME Revenues [Abstract] Net premiums earned Fees and commission income Fees and Commissions Net investment income Net realized and unrealized gains (losses) Gain (Loss) on Investments Other income Other Income Total income EXPENSES Benefits, Losses and Expenses [Abstract] Life and annuity policy benefits Policyholder Benefits and Claims Incurred, Net, Life and Annuity General and administrative expenses General and Administrative Expense Interest expense Interest Expense Net foreign exchange losses (gains) Foreign Currency Transaction Gain (Loss), before Tax Total expenses Benefits, Losses and Expenses INCOME TAXES Income Tax Expense (Benefit) NET EARNINGS FROM CONTINUING OPERATIONS Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest NET EARNINGS (LOSS) FROM DISCONTINUING OPERATIONS, NET OF INCOME TAX EXPENSE Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: Net loss (earnings) attributable to noncontrolling interest Liability for Claims and Claims Adjustment Expense [Table] Liability for Claims and Claims Adjustment Expense [Table] Non-Life Run-off Segment, Atrium Segment, and Starstone Segment Non-Life Run-off Segment, Atrium Segment, and Starstone Segment [Member] Non-Life Run-off Segment, Atrium Segment, and Starstone Segment [Member] Liability for Claims and Claims Adjustment Expense [Line Items] Liability for Claims and Claims Adjustment Expense [Line Items] Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Balance as at January 1 Liability for Claims and Claims Adjustment Expense Less: reinsurance reserves recoverable Less: deferred charge on retroactive reinsurance Deferred Costs Net balance as at January 1 Liability for Unpaid Claims and Claims Adjustment Expense, Net Net incurred losses and LAE: Liability for Unpaid Claims and Claims Adjustment Expense, Activity in Liability [Abstract] Current period Prior periods Total net incurred losses and LAE Net paid losses: Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract] Current period Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year Prior periods Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Total net paid losses Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Effect of exchange rate movement Liability for Unpaid Claims and Claims Adjustment Expense, Foreign Currency Translation Gain (Loss) Acquired on purchase of subsidiaries Liability for Unpaid Claims and Claims Adjustment Expense, Business Acquisitions Assumed business Liability For Unpaid Claims And Claims Adjustment Expense, Assumed Business Liability For Unpaid Claims And Claims Adjustment Expense, Assumed Business Ceded business Liability For Unpaid Claims And Claims Adjustment Expense, Ceded Business Liability For Unpaid Claims And Claims Adjustment Expense, Ceded Business Net balance as at December 31 Plus: reinsurance reserves recoverable Plus: deferred charge on retroactive reinsurance Balance as at December 31 Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Fair Value Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] 12 Months or Greater Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Less Than 12 Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Total Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Gross Unrealized Losses Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract] 12 Months or Greater Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Less Than 12 Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Total Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss Number of securities classified as available-for-sale in an unrealized loss position Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions Number of securities classified as available-for-sale in an unrealized loss position for twelve months or longer Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Domestic (Bermuda) Current Federal Tax Expense (Benefit) Foreign Current Foreign Tax Expense (Benefit) Total current tax expense Current Income Tax Expense (Benefit) Deferred: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Domestic (Bermuda) Deferred Federal Income Tax Expense (Benefit) Foreign Deferred Foreign Income Tax Expense (Benefit) Total deferred tax expense Deferred Income Tax Expense (Benefit) Total tax expense on continuing operations Other Investments [Table] Other Investments [Table] Other Investments Private equities and private equity funds Private Equity Funds [Member] Fixed income funds Fixed Income Funds [Member] Fixed income hedge funds Hedge Funds, Fixed Income [Member] Hedge Funds, Fixed Income [Member] Equity funds Equity Funds [Member] Multi-strategy hedge fund Hedge Funds, Multi-strategy [Member] Real estate debt fund Real Estate Funds [Member] CLO equities CLO Equity [Member] CLO Equity [Member] CLO equity funds CLO Equity Funds [Member] CLO Equity Funds [Member] Other Other Long-term Investments [Member] CLO Equity Fund One CLO Equity Fund One [Member] CLO Equity Fund One [Member] CLO Equity Fund Two CLO Equity Fund Two [Member] CLO Equity Fund Two [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Other Investments [Line Items] Other Investments [Line Items] [Line Items] for Other Investments Other investments, at fair value Other Investments Valuation lag period Other Investments, Valuation Lag Period Other Investments, Valuation Lag Period Imposed lock-up period (up to) (years) Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Redemption Restriction, Period in Effect Number of days to give notice for quarterly hedge fund redemptions Notice Period For Redemption Of Hedge Fund Notice period for redemption of hedge fund. Redemption request period (days) Other Investments, Redemption Request Period Other Investments, Redemption Request Period Number of CLO equity funds Other Investments, Number of Funds Number of Funds Invested in Equity Tranches of Term-Financed Securitizations of Diversified Pools of Corporate Bank Loans CLO equity fund pay out period (years) Other Investments, Fund Payout Period Equity Fund, Payout Period Gates or side-pocket investments Investment, Fair Value Disclosure, Subject to Gates or Side Pocket Restrictions Investment, Fair Value Disclosure, Subject to Gates or Side Pocket Restrictions Unfunded commitments Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Restricted shares and restricted share awards Restricted Stock and Restricted Stock Units [Member] Restricted Stock and Restricted Stock Units [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Number of Shares, Nonvested - January 1 (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Number of Shares, Granted (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Number of Shares, Vested (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Number of Shares, Forfeited (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Number of Shares, Nonvested - December 31 (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Weighted Average Fair Value of the Award, Nonvested - January 1 (dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Weighted Average Fair Value of the Award, Granted (dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted Average Fair Value of the Award, Vested (dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Weighted Average Fair Value of the Award, Forfeited (dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Weighted Average Fair Value of the Award, Nonvested - December 31 (dollars per share) Compensation costs Allocated Share-based Compensation Expense Unrecognized compensation cost Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options Unrecognized compensation cost, period of recognition Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Voting ordinary shares Voting Common Stock [Member] Voting Common Stock. Series A non-voting convertible ordinary shares Common Class A [Member] Series C non-voting convertible ordinary shares Common Class C [Member] Series E non-voting convertible ordinary shares Common Class E [Member] Common Class E [Member] Series C non-voting preferred shares Series C Preferred Stock [Member] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] ASSETS Assets [Abstract] Cash and cash equivalents Balances due from subsidiaries Receivables From Subsidiaries Receivables From Subsidiaries Investments in subsidiaries Investments in Subsidiaries Investments in Subsidiaries Other assets Other Assets TOTAL ASSETS LIABILITIES Liabilities [Abstract] Loans payable Long-term Debt Balances due to subsidiaries Payables to Subsidiaries Payables to Subsidiaries Other liabilities Other Liabilities TOTAL LIABILITIES Liabilities SHAREHOLDERS’ EQUITY Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Ordinary shares Common Stock, Value, Issued Series C Preferred Shares (issued and outstanding 2016: 388,571; 2015: nil) Preferred Stock, Value, Issued Treasury shares at cost (Preferred shares 2016: 388,571; Series A non-voting convertible ordinary shares 2015: 2,972,892) Treasury Stock, Value Additional paid-in capital Additional Paid in Capital Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Retained earnings Retained Earnings (Accumulated Deficit) Total Enstar Group Limited Shareholders’ Equity Stockholders' Equity Attributable to Parent TOTAL LIABILITIES, REDEEMABLE NONCONTROLLING INTEREST AND SHAREHOLDERS’ EQUITY Liabilities and Equity Parenthetical Disclosures [Abstract] Balance Sheet Related Disclosures [Abstract] Common shares, par value (dollars per share) Common Stock, Par or Stated Value Per Share Preferred shares, par value (dollars per share) Preferred Stock, Par or Stated Value Per Share Share capital, authorized (shares) Common and Preferred Stock, Shares Authorized Common and Preferred Stock, Shares Authorized Ordinary shares, shares issued (shares) Common Stock, Shares, Issued Ordinary shares, outstanding (shares) Common Stock, Shares, Outstanding Preferred shares, issued (shares) Preferred Stock, Shares Issued Preferred shares, outstanding (shares) Preferred Stock, Shares Outstanding Treasury shares (shares) Treasury Stock, Shares INVESTMENTS Investment [Text Block] Product Concentration Risk Product Concentration Risk [Member] Segment Concentration Risk Segment Concentration Risk [Member] Segment Concentration Risk [Member] Liability for Unpaid Claims and Claims Adjustment Expense Liability for Unpaid Claims and Claims Adjustment Expense [Member] Liability for Unpaid Claims and Claims Adjustment Expense [Member] Liability for Unpaid Claims and Claims Adjustment Expense, Net Liability for Unpaid Claims and Claims Adjustment Expense, Net [Member] Liability for Unpaid Claims and Claims Adjustment Expense, Net [Member] Liability Claims and Claims Adjustment Expense Liability Claims and Claims Adjustment Expense [Member] Liability Claims and Claims Adjustment Expense [Member] Atrium Segment StarStone Segment Asbestos liabilities Reserve for Asbestos Loss [Member] Reserve for Asbestos Loss [Member] Environmental liabilities Reserve For Environmental Loss [Member] Reserve For Environmental Loss [Member] General casualty liabilities Reserve for General Casualty Loss [Member] Reserve for General Casualty Loss [Member] Workers' compensation liabilities Reserve for Worker Compensation Loss [Member] Reserve for Worker Compensation Loss [Member] Other liabilities Reserve for Other Loss [Member] Reserve for Other Loss [Member] Net incurred losses and loss adjustment expenses Net incurred losses and LAE, current period Current period net earned premium Current Year Premiums Earned, Net Current Year Premiums Earned, Net Net incurred losses and LAE, prior period Increase (reduction) in estimates of net ultimate losses, prior period Estimates of Net Ultimate Losses, Period Increase (Decrease), Prior Years Estimates of Net Ultimate Losses, Period Increase (Decrease), Prior Years Increase (reduction) in provisions for bad debt, prior period Provision For Doubtful Accounts, Prior Years Provision For Doubtful Accounts, Prior Years Increase (reduction) in provisions for unallocated LAE, prior period Provision For Unallocated Claim Adjustment Expense, Prior Years Provision For Unallocated Claim Adjustment Expense, Prior Years Amortization of fair value adjustments, prior period Claims And Claims Adjustment Expense, Amortization Of Fair Value Adjustments, Prior Years Claims And Claims Adjustment Expense, Amortization Of Fair Value Adjustments, Prior Years Net change in IBNR reserves, prior period Liability For Unpaid Claims And Claims Adjustment Expense, Incurred But Not Reported Claims Amount, Period Increase (Decrease), Prior Years Liability For Unpaid Claims And Claims Adjustment Expense, Incurred But Not Reported Claims Amount, Period Increase (Decrease), Prior Years Net incurred loss development Estimate Of Net Ultimate Losses, Net Incurred Development Loss, Period Increase (Decrease) Estimate Of Net Ultimate Losses, Net Incurred Development Loss, Period Increase (Decrease) Amortization of deferred charges, prior period Deferred Costs, Current And Noncurrent, Amortization, Prior Year Deferred Costs, Current And Noncurrent, Amortization, Prior Year Total number of commutations Number of Commutations and Policy Buybacks Number of Commutations and Policy Buybacks Net change in case and LAE reserves, prior period Change in Case and Loss Adjustment Expense Reserve Period Increase (Decrease), Prior Years Change in Case and Loss Adjustment Expense Reserve Period Increase (Decrease), Prior Years Net losses paid, prior period Number of partial commutations of the Company's top 10 ceded recoverables Number of Partial Commutations of Top Ten Ceded Recoverables Number of Partial Commutations of Top Ten Ceded Recoverables Number of partial commutations of the Company's top 10 assumed exposures Number of Partial Commutations of Top Ten Assumed Exposures Number of Partial Commutations of Top Ten Assumed Exposures Net incurred liabilities settled by way of commutation Change in Case and Loss Adjustment Expense, Reserve, Settlements Change in Case and Loss Adjustment Expense, Reserve, Settlements Assumed incurred liabilities Change in Case and Loss Adjustment Expense Reserve Incurred Reserves Settlements Change in Case and Loss Adjustment Expense Reserve Incurred Reserves Settlements Ceded incurred reinsurance recoverables Change in Case and Loss Adjustment Expense, Reserve, Assumed Reserves, Settlements Change in Case and Loss Adjustment Expense, Reserve, Assumed Reserves, Settlements Estimate of net ultimate liability for asbestos and environmental claims Liability for Asbestos and Environmental Claims, Net Estimate of gross ultimate liability for asbestos and environmental claims Liability for Asbestos and Environmental Claims, Gross % of Total Concentration Risk, Percentage Income Statement [Abstract] Net realized and unrealized gains (losses) Net foreign exchange losses EARNINGS BEFORE INCOME TAXES NET EARNINGS Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Basic: Earnings Per Share, Basic [Abstract] Net earnings from continuing operations (dollars per share) Income (Loss) from Continuing Operations, Per Basic Share Net earnings (loss) from discontinuing operations (dollars per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share Net earnings per ordinary share (dollars per share) Earnings Per Share, Basic Diluted: Earnings Per Share, Diluted [Abstract] Net earnings from continuing operations (dollars per share) Income (Loss) from Continuing Operations, Per Diluted Share Net earnings (loss) from discontinuing operations (dollars per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share Net earnings per ordinary share (dollars per share) Earnings Per Share, Diluted Weighted average ordinary shares outstanding: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Weighted average ordinary shares outstanding - basic (shares) Weighted Average Number of Shares Outstanding, Basic Weighted average ordinary shares outstanding - diluted (shares) Weighted Average Number of Shares Outstanding, Diluted Reversal of amortization of fair value adjustment Reversal of Amortization of Fair Value Adjustment [Member] Reversal of Amortization of Fair Value Adjustment [Member] Amortization of fair value adjustments Amortization of Fair Value Adjustment [Member] Amortization of Fair Value Adjustment [Member] Interest expense adjustment Interest Expense Adjustment [Member] Interest Expense Adjustment [Member] Amortization of fair value adjustment related to acquired losses and LAE liabilities and reinsurance balances recoverable Amortization of Finite-Lived Intangible Assets Adjustment [Member] Amortization of Finite-Lived Intangible Assets Adjustment [Member] Income tax adjustment Income Tax Adjustment [Member] Income Tax Adjustment [Member] Segment Information Segment Reporting Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Share Capital Series B Convertible Participating Non-Voting Perpetual Preferred Stock Series B Convertible Participating Non Voting Perpetual Preferred Stock [Member] Series B Convertible Participating Non Voting Perpetual Preferred Stock [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Ordinary Shares Common Stock [Member] Preferred Stock Preferred Stock [Member] Treasury Shares Treasury Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Currency translation adjustment Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Defined benefit pension liability Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Unrealized gains (losses) on investments Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Retained Earnings Retained Earnings [Member] Noncontrolling Interest (excludes redeemable noncontrolling interests) Noncontrolling Interest [Member] Foreign currency translation adjustments Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest [Member] Net movement in unrealized holding losses on investments Accumulated Net Investment Gain (Loss) Attributable to Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance, beginning of year Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Issue of shares Stock Issued During Period, Value, New Issues Issue of shares and warrants Adjustments to Additional Paid in Capital, Stock and Warrant Issued Adjustments to Additional Paid in Capital, Stock and Warrant Issued Conversion of convertible securities Stock Issued During Period, Value, Conversion of Convertible Securities Warrants exercised Stock Issued During Period, Value, Warrant Exercised Stock Issued During Period, Value, Warrant Exercised Amortization of share-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Equity attributable to purchase of noncontrolling shareholders’ interest in subsidiaries Stock Issued During Period, Value, Acquisitions Purchase of noncontrolling shareholders' interest in subsidiaries Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Change in defined benefit pension liability Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Net earnings (loss) Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Change in redemption of redeemable noncontrolling interests Increase in Carrying Amount of Redeemable Preferred Stock Return of capital Noncontrolling Interest, Decrease from Return of Capital Noncontrolling Interest, Decrease from Return of Capital Dividends paid Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Contribution of capital Noncontrolling Interest, Increase from Subsidiary Equity Issuance Reallocation from (to) redeemable noncontrolling interest Reallocation From (To) Redeemable Noncontrolling Interest Reallocation From (To) Redeemable Noncontrolling Interest Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Balance, end of year Statutory Accounting Practices [Table] Statutory Accounting Practices [Table] Jurisdiction [Axis] Jurisdiction [Axis] Statutory Accounting Practices, Jurisdiction [Domain] Statutory Accounting Practices, Jurisdiction [Domain] Bermuda BERMUDA United Kingdom UNITED KINGDOM United States United States and Canada United States and Canada [Member] United States and Canada [Member] Switzerland SWITZERLAND Liechtenstein LIECHTENSTEIN Statutory Accounting Practices [Line Items] Statutory Accounting Practices [Line Items] Target statutory capital and surplus percent Statutory Accounting Practices, Statutory Capital and Surplus Required, Percent Statutory Accounting Practices, Statutory Capital and Surplus Required, Percent Restricted net assets of consolidated subsidiaries Amount Of Restricted Net Assets For Consolidated Subsidiaries Amount Of Restricted Net Assets For Consolidated Subsidiaries Minimum liquidity ratio percent (not less than) Statutory Accounting Practices, Minimum Liquidity Ratio Statutory Accounting Practices, Minimum Liquidity Ratio Maximum percentage reduction in total statutory capital without prior approval of Bermuda regulator (percent) (or more) Statutory Accounting Practices, Minimum Percent Reduction To Prior Year Statutory Capital Prohibited Statutory Accounting Practices, Minimum Percent Reduction To Prior Year Statutory Capital Prohibited Minimum solvency requirement Statutory Accounting Practices, Minimum Solvency Requirement, Excess Amount Statutory Accounting Practices, Minimum Solvency Requirement, Excess Amount Minimum capital requirements Statutory Accounting Practices, Minimum Capital Requirement, Excess Amount Statutory Accounting Practices, Minimum Capital Requirement, Excess Amount Number of syndicates Number of Syndicates Number of Syndicates Minimum levels of risk-based capital Statutory Accounting Practices, Risk Based Capital Requirement, Excess Amount Statutory Accounting Practices, Risk Based Capital Requirement, Excess Amount Maximum dividend payout without prior approval Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval Minimum Swiss solvency test margin Statutor yAccounting Practices, Swiss Solvency Test Minimum Solvency Requirement, Excess Amount Statutor yAccounting Practices, Swiss Solvency Test Minimum Solvency Requirement, Excess Amount FUNDS HELD - DIRECTLY MANAGED Funds Held, Directly Managed [Text Block] Funds Held, Directly Managed [Text Block] Discontinued Operations and Disposal Groups [Abstract] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] Pavonia Pavonia [Member] Pavonia [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Discontinued operations, held-for-sale Discontinued Operations, Held-for-sale [Member] Short-term investments Short-term Investments [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Disposal Group, Including Discontinued Operation, Unclassified Balance Sheet Disclosures [Abstract] Disposal Group, Including Discontinued Operation, Unclassified Balance Sheet Disclosures [Abstract] Assets: Disposal Group, Including Discontinued Operation, Assets [Abstract] Trading, at fair value Disposal Group, Including Discontinued Operation, Trading Securities, Debt Disposal Group, Including Discontinued Operation, Trading Securities, Debt Fixed maturities, held-to-maturity, at amortized cost Disposal Group, Including Discontinued Operation, Held-to-maturity Securities Disposal Group, Including Discontinued Operation, Held-to-maturity Securities Equities, trading, at fair value Disposal Group, Including Discontinued Operation, Trading Securities, Equity Disposal Group, Including Discontinued Operation, Trading Securities, Equity Other investments, at fair value Disposal Group, Including Discontinued Operation, Other Investments Disposal Group, Including Discontinued Operation, Other Investments Cash and cash equivalents Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents Restricted cash and cash equivalents Disposal Group, Including Discontinued Operation, Restricted Cash and Cash Equivalents Disposal Group, Including Discontinued Operation, Restricted Cash and Cash Equivalents Deferred tax assets Disposal Group, Including Discontinued Operation, Deferred Tax Assets Reinsurance balances recoverable Disposal Group, Including Discontinued Operation, Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments Disposal Group, Including Discontinued Operation, Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments Other assets Disposal Group, Including Discontinued Operation, Other Assets Total assets held for sale Disposal Group, Including Discontinued Operation, Assets Liabilities: Disposal Group, Including Discontinued Operation, Liabilities [Abstract] Policy benefits for life and annuity contracts Disposal Group, Including Discontinued Operation, Liability for Future Policy Benefits Disposal Group, Including Discontinued Operation, Liability for Future Policy Benefits Other liabilities Disposal Group, Including Discontinued Operation, Other Liabilities Total liabilities held for sale Disposal Group, Including Discontinued Operation, Liabilities Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract] Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract] INCOME Disposal Group, Including Discontinued Operation, Revenues [Abstract] Disposal Group, Including Discontinued Operation, Revenues [Abstract] Net premiums earned Disposal Group, Including Discontinued Operation, Premiums Earned, Net Disposal Group, Including Discontinued Operation, Premiums Earned, Net Net investment income Disposal Group, Including Discontinued Operation, Net Investment Income Disposal Group, Including Discontinued Operation, Net Investment Income Net realized and unrealized gains (losses) Disposal Group, Including Discontinued Operation, Gain (Loss) on Investments Disposal Group, Including Discontinued Operation, Gain (Loss) on Investments Other income Disposal Group, Including Discontinued Operation, Other Income Total income Disposal Group, Including Discontinued Operation, Revenue EXPENSES Disposal Group, Including Discontinued Operation, Expenses [Abstract] Disposal Group, Including Discontinued Operation, Expenses [Abstract] Life and annuity policy benefits Disposal Group, Including Discontinued Operation, Policyholder Benefits and Claims Incurred, Net, Life and Annuity Disposal Group, Including Discontinued Operation, Policyholder Benefits and Claims Incurred, Net, Life and Annuity Acquisition costs Disposal Group, Including Discontinued Operation, Business Combination, Acquisition Related Costs Disposal Group, Including Discontinued Operation, Business Combination, Acquisition Related Costs General and administrative expenses Disposal Group, Including Discontinued Operation, General and Administrative Expense Other expenses Disposal Group, Including Discontinued Operation, Other Expense Total expenses Disposal Group, Including Discontinued Operation, Benefits, Losses and Expenses Disposal Group, Including Discontinued Operation, Benefits, Losses and Expenses EARNINGS (LOSS) BEFORE INCOME TAXES Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax INCOME TAXES Discontinued Operation, Tax Effect of Discontinued Operation NET EARNINGS FROM DISCONTINUED OPERATIONS Net Cash Provided by (Used in) Discontinued Operations [Abstract] Net Cash Provided by (Used in) Discontinued Operations [Abstract] Operating activities Cash Provided by (Used in) Operating Activities, Discontinued Operations Investing activities Cash Provided by (Used in) Investing Activities, Discontinued Operations Financing Activities Cash Provided by (Used in) Financing Activities, Discontinued Operations Change in cash of businesses held for sale Net Cash Provided by (Used in) Discontinued Operations Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Carrying Value Reported Value Measurement [Member] Life Settlement Life Settlement Investment [Member] Life Settlement Investment Life settlements Other Investments Carried at Cost, Fair Value Disclosure Other Investments Carried at Cost, Fair Value Disclosure Redeemable Noncontrolling Interest, by Legal Entity [Table] Redeemable Noncontrolling Interest, by Legal Entity [Table] Trident Trident [Member] Trident [Member] Dowling Dowling [Member] Dowling [Member] Ownership [Axis] Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] [Domain] for Ownership [Axis] North Bay North Bay Holdings Limited [Member] North Bay Holdings Limited [Member] Atrium Atrium [Member] Atrium [Member] Arden Arden [Member] Arden [Member] Northshore Northshore [Member] Northshore [Member] StarStone Holdings StarStone Holdings [Member] StarStone Holdings [Member] Redeemable Noncontrolling Interest [Line Items] Redeemable Noncontrolling Interest [Line Items] Ownership interest held by noncontrolling owners Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Ownership interest held by parent Noncontrolling Interest, Ownership Percentage by Parent Capital contributions Temporary Equity, Stock Issued During Period, Value, New Issues Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] Balance at beginning of year Redeemable Noncontrolling Interest, Equity, Carrying Amount Capital contributions Temporary Equity, Increase From Capital Contributions Temporary Equity, Increase From Capital Contributions Dividends paid Temporary Equity, Accretion of Dividends Net earnings (loss) attributable to RNCI Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Accumulated other comprehensive income (loss) attributable to RNCI Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Redeemable Noncontrolling Interest Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Redeemable Noncontrolling Interest Transfer from noncontrolling interest Reclassifications of Temporary to Permanent Equity Change in redemption value of RNCI Temporary Equity, Accretion to Redemption Value Balance at end of year Goodwill [Roll Forward] Goodwill [Roll Forward] Goodwill, Beginning balance Goodwill, Acquired during the year Goodwill, Acquired During Period Goodwill, Ending balance Finite-lived Intangible Assets [Roll Forward] Finite-lived Intangible Assets [Roll Forward] Intangible assets with a definite life, Beginning balance Finite-Lived Intangible Assets, Net Intangible assets with a definite life, Acquired during the year Finite-lived Intangible Assets Acquired Intangible assets with a definite life, Amortization Amortization of Intangible Assets Intangible assets with a definite life, Ending balance Indefinite-lived Intangible Assets [Roll Forward] Indefinite-lived Intangible Assets [Roll Forward] Intangible assets with an indefinite life, Beginning balance Indefinite-Lived Intangible Assets (Excluding Goodwill) Intangible assets with an indefinite life, Acquired during the year Indefinite-lived Intangible Assets Acquired Intangible assets with an indefinite life, Ending balance Goodwill and Intangible Assets [Roll Forward] Goodwill and Intangible Assets [Roll Forward] Goodwill and Intangible Assets [Roll Forward] Goodwill and intangible assets, Beginning Balance Intangible Assets, Net (Including Goodwill) Goodwill and intangible assets, Acquired during the year Goodwill And Intangible Assets Acquired During Period Goodwill And Intangible Assets Acquired During Period Intangible assets with a definite life, Amortization Goodwill and intangible assets, Ending balance Movement in Intangible Assets Arising from Insurance Contracts Acquired in Business Combination [Roll Forward] Movement in Intangible Assets Arising from Insurance Contracts Acquired in Business Combination [Roll Forward] Intangible assets with a definite life - FVA, Beginning balance Intangible Assets Arising from Insurance Contracts Acquired in Business Combination Intangible assets with a definite life - FVA, Acquired during the period Intangible Assets Arising from Insurance Contracts Acquired in Business Combination, Additions Intangible assets with a definite life - FVA, Amortization Intangibles Assets Arising from Insurance Contracts Acquired in Business Combination, Amortization Expense Intangible assets with a definite life - FVA, Ending balance Deferred Charges [Roll Forward] Deferred Charges [Roll Forward] Deferred Charges [Roll Forward] Other assets - Deferred Charge, Acquired during the year Deferred Costs, Current And Noncurrent, Acquired Deferred Costs, Current And Noncurrent, Acquired Other assets - Deferred Charge, Amortization Deferred Costs, Current And Noncurrent, Amortization Deferred Costs, Current And Noncurrent, Amortization Number of segments Number of Reportable Segments Syndicate underwriting capacity percentage Percentage Of Underwriting Capacity And Capital Provided To Syndicate Percentage of Underwriting Capacity and Capital Provided to Syndicate Earnings Per Share [Abstract] Comparison of Basic and Diluted Earnings per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Europe Europe [Member] Minimum required statutory capital and surplus Statutory Accounting Practices, Statutory Capital and Surplus Required Actual statutory capital and surplus Statutory Accounting Practices, Statutory Capital and Surplus, Balance Statutory income Statutory Accounting Practices, Statutory Net Income Amount Financial Information of Held-For-Sale Business Disposal Groups, Including Discontinued Operations [Table Text Block] Amortized Cost Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis, Rolling Maturity [Abstract] One year or less Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Amortized Cost Basis More than one year through two years Available-for-sale Securities, Debt Maturities, Rolling Year Two, Amortized Cost Basis Available-for-sale Securities, Debt Maturities, Rolling Year Two, Amortized Cost Basis More than two years through five years Available-for-sale Securities, Debt Maturities, Rolling Year Three Through Five, Amortized Cost Basis Available-for-sale Securities, Debt Maturities, Rolling Year Three Through Five, Amortized Cost Basis More than five years through ten years Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Amortized Cost Basis More than ten years Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Amortized Cost Basis Securities without single maturity date Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis Amortized Cost Available-for-sale Debt Securities, Amortized Cost Basis Fair Value Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturity [Abstract] One year or less Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value More than one year through two years Available-for-sale Securities, Debt Maturities, Rolling Year Two, Fair Value Available-for-sale Securities, Debt Maturities, Rolling Year Two, Fair Value More than two years through five years Available-for-sale Securities, Debt Maturities, Rolling Year Three Through Five, Fair Value Available-for-sale Securities, Debt Maturities, Rolling Year Three Through Five, Fair Value More than five years through ten years Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value More than ten years Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Fair Value Securities without single maturity date Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value Fair Value Available-for-sale Securities, Debt Securities % of Total Fair Value Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturity, Percent of Fair Value [Abstract] Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturity, Percent of Fair Value [Abstract] One year or less Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value, Percent Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value, Percent More than one year through two years Available-for-sale Securities, Debt Maturities, Rolling Year Two, Fair Value, Percent Available for sale securities debt maturities after one through two years percent of fair value. More than two years through five years Available-for-sale Securities, Debt Maturities, Rolling Year Three Through Five, Fair Value, Percent Available for sale securities debt maturities after two through five years percent of fair value. More than five years through ten years Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value, Percent Available for sale securities debt maturities after five through ten years percent of fair value. More than ten years Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Fair Value, Percent Available for sale securities debt maturities after ten years percent of fair value. Securities without single maturity date Available-For-Sale Securities, Debt Maturities, Without Single Maturity Date, Fair Value, Percent Available-For-Sale Securities, Debt Maturities, Without Single Maturity Date, Fair Value, Percent Percentage of Total Fair Value Available-for-sale Securities, Debt Securities, Percent Available for sale securities debt securities percent of fair value. Quarterly Financial Information Disclosure [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Pension Plan Pension Plan [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined contribution plan expense Defined Contribution Plan, Cost Recognized Pension expense Pension Expense Unfunded liability Defined Benefit Plan, Funded Status of Plan Accrued liability Pension and Other Postretirement Defined Benefit Plans, Liabilities Hillhouse Hillhouse [Member] Hillhouse [Member] Hillhouse affiliates Hillhouse Affiliates [Member] Hillhouse Affiliates [Member] Affiliated entity Affiliated Entity [Member] Ownership percentage of ordinary shares Common Stock Ownership Percentage Common Stock Ownership Percentage Economic ownership percentage Common Stock Economic Ownership Percentage Common Stock Economic Ownership Percentage Investments in funds Other investments Funds held Funds Held [Member] Funds Held [Member] Life settlements and other Life Settlements and Other [Member] Life Settlements and Other [Member] Gross investment income Gross Investment Income, Operating Investment expenses Investment Income, Investment Expense Net investment income Cash-Settled Stock Appreciation Rights Stock Appreciation Rights (SARs) [Member] Exercise period Share Based Compensation Arrangement By Share Based Payment Awards, Exercise Period Share based compensation arrangement by share based payment awards exercise period. Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Balance, beginning of year, Number of SARs (shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number Exercised, Number of SARs (shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised Forfeited, Number of SARs (shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures Balance, end of year, Number of SARs (shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Balance, beginning of year, Weighted Average Exercise Price of SARs (dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price Exercised, Weighted Average Exercise Price of SARS (dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised, Weighted Average Exercise Price Forfeited, Weighted Average Exercise Price of SARs (dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures, Weighted Average Exercise Price Balance, end of year, Weighted Average Exercise Price of SARs (dollars per share) Balance, end of year, Weighted Average Remaining Contractual Term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms Balance, end of year, Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding Closing price per share, ordinary shares (dollars per share) Share Price Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Weighted average fair value per SAR (dollars per share) Weighted-average volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate Weighted-average risk-free interest rate Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Weighted Average Risk Free Interest Rate Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Weighted Average Risk Free Interest Rate Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Summary of Investments, Other than Investments in Related Parties [Abstract] Summary of Investments, Other than Investments in Related Parties [Table] Summary of Investments, Other than Investments in Related Parties [Table] Investments by Category [Axis] Investments by Category [Axis] Marketable Securities and Investments Held at Cost [Domain] Marketable Securities and Investments Held at Cost [Domain] Trading securities Trading Securities [Member] Equities Equity Securities, Investment Summary [Member] Other investments, at fair value Other Investments, at Fair Value [Member] Other Investments, at Fair Value [Member] Other investments, at cost Other Investments, at Cost [Member] Other Investments, at Cost [Member] Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items] Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items] Cost Summary of Investments, Other than Investments in Related Parties, Cost Fair Value Summary of Investments, Other than Investments in Related Parties, Fair Value Amount at which shown in the balance sheet Summary of Investments, Other than Investments in Related Parties, Carrying Amount Fair value of other investments in funds or companies owned by or affiliated with related parties Residential mortgage-backed Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Assets, Fair Value Disclosure [Abstract] Assets, Fair Value Disclosure [Abstract] Total investments Other investments Derivative instruments Liabilities, Fair Value Disclosure [Abstract] Liabilities, Fair Value Disclosure [Abstract] Earnings Per Share Earnings Per Share [Text Block] Valuation allowance Deferred Tax Assets, Valuation Allowance Increase (decrease) in valuation allowance Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Reversal of accrued interest and penalties related to unrecognized tax benefits Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense Accrued interest and penalties related to unrecognized tax benefits Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Fair value adjustments, policy benefits for life and annuity contracts Policy Benefits For Life And Annuity Contracts [Member] Policy Benefits For Life And Annuity Contracts [Member] Goodwill Impairment of goodwill Goodwill, Impairment Loss Intangible assets useful life Finite-Lived Intangible Asset, Useful Life Amortization of intangible assets Amortization of Deferred Charges Impairment of intangible assets with a definite life Impairment of Intangible Assets, Finite-lived Intangible assets FVA amortization (accretion) Amortization of deferred charges - related to reduction in liability for losses and LAE Deferred Costs, Current And Noncurrent, Amortization Related To Reduction In Liability For Claims And Claims Adjustment Expense Deferred Costs, Current And Noncurrent, Amortization Related To Reduction In Liability For Claims And Claims Adjustment Expense Amortization of deferred charges - primarily related to change in expected return on underlying assets Deferred Costs, Current And Noncurrent, Amortization Related To Change In Expected Return On Underlying Assets Deferred Costs, Current And Noncurrent, Amortization Related To Change In Expected Return On Underlying Assets Intangible assets with a definite life, fair value adjustments Gross, premiums written Premiums Written, Gross Ceded, premiums written Ceded Premiums Written Net, premiums written Premiums Written, Net Gross, premiums earned Ceded, premiums earned Earnings before Income Taxes Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Tax Expense for Income Taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Reconciliation of Earnings before Income Taxes Computed by Applying Effective Rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Components of Deferred Tax Assets and Deferred Tax Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Summary of Operating Loss Carryforwards Summary of Operating Loss Carryforwards [Table Text Block] Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Summary of Income Tax Examinations Summary of Income Tax Examinations [Table Text Block] Life Settlements Life Settlements [Member] Life Settlements [Member] Other investments, at cost Other Investments and Securities, at Cost Amount of net investment income included in earnings attributable to investments in life settlements Impairment charges recognized in the period Other than Temporary Impairment Losses, Investments Number of Contracts Life Settlement Contracts, Investment Method, Number of Contracts, Rolling Maturity [Abstract] 0 – 1 year Life Settlement Contracts, Investment Method, Number of Contracts, Maturing in Next Rolling Twelve Months 1 – 2 years Life Settlement Contracts, Investment Method, Number of Contracts, Maturing in Rolling Year Two 2 – 3 years Life Settlement Contracts, Investment Method, Number of Contracts, Maturing in Rolling Year Three 3 – 4 years Life Settlement Contracts, Investment Method, Number of Contracts, Maturing in Rolling Year Four 4 – 5 years Life Settlement Contracts, Investment Method, Number of Contracts, Maturing in Rolling Year Five Thereafter Life Settlement Contracts, Investment Method, Number of Contracts, Maturing after Rolling Year Five Total Life Settlement Contracts, Investment Method, Number of Contracts Carrying Value Life Settlement Contracts, Investment Method, Carrying Amount, Rolling Maturity [Abstract] 0 – 1 year Life Settlement Contracts, Investment Method, Carrying Amount, Maturing in Next Rolling Twelve Months 1 – 2 years Life Settlement Contracts, Investment Method, Carrying Amount, Maturing in Rolling Year Two 2 – 3 years Life Settlement Contracts, Investment Method, Carrying Amount, Maturing in Rolling Year Three 3 – 4 years Life Settlement Contracts, Investment Method, Carrying Amount, Maturing in Rolling Year Four 4 – 5 years Life Settlement Contracts, Investment Method, Carrying Amount, Maturing in Rolling Year Five Thereafter Life Settlement Contracts, Investment Method, Carrying Amount, Maturing after Rolling Year Five Total Life Settlement Contracts, Investment Method, Carrying Amount Face Value (Death Benefits) Life Settlement Contracts, Investment Method, Face Value, Rolling Maturity [Abstract] 0 – 1 year Life Settlement Contracts, Investment Method, Face Value, Maturing in Next Rolling Twelve Months 1 – 2 years Life Settlement Contracts, Investment Method, Face Value, Maturing in Rolling Year Two 2 – 3 years Life Settlement Contracts, Investment Method, Face Value, Maturing in Rolling Year Three 3 – 4 years Life Settlement Contracts, Investment Method, Face Value, Maturing in Rolling Year Four 4 – 5 years Life Settlement Contracts, Investment Method, Face Value, Maturing in Rolling Year Five Thereafter Life Settlement Contracts, Investment Method, Face Value, Maturing after Rolling Year Five Total Life Settlement Contracts, Investment Method, Face Value Life Settlement Contracts, Investment Method, Premiums to be Paid, Fiscal Year Maturity [Abstract] Life Settlement Contracts, Investment Method, Premiums to be Paid, Fiscal Year Maturity [Abstract] Life insurance premiums payable in 2017 Life Settlement Contracts, Investment Method, Premiums to be Paid in Next Twelve Months Life insurance premiums payable in 2018 Life Settlement Contracts, Investment Method, Premiums to be Paid in Rolling Year Two Life insurance premiums payable in 2019 Life Settlement Contracts, Investment Method, Premiums to be Paid in Rolling Year Three Life insurance premiums payable in 2020 Life Settlement Contracts, Investment Method, Premiums to be Paid in Rolling Year Four Life insurance premiums payable in 2021 Life Settlement Contracts, Investment Method, Premiums to be Paid in Rolling Year Five RSA RSA Insurance Group PLC [Member] RSA Insurance Group PLC [Member] QBE QBE Insurance Group Limited [Member] QBE Insurance Group Limited [Member] Coca-Cola Coca-Cola [Member] Coca-Cola [Member] Allianz Allianz [Member] Allianz [Member] Shelbourne RITC Shelbourne RITC [Member] Shelbourne RITC [Member] The Doctors Company and its affiliates The Doctors Company [Member] The Doctors Company [Member] Sun Life Sunset Life [Member] Sunset Life [Member] Voya Financial Voya Financial Incorporation [Member] Voya Financial Incorporation [Member] Reciprocal of America Reciprocal Of America [Member] Reciprocal of America. Lloyd's syndicate Lloyd's Syndicate Member [Member] Lloyd's Syndicate Member [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent event Subsequent Event [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other assets Other Assets [Member] Assumed business, net Liability For Unpaid Claims And Claims Adjustment Expense, Assumed Business, Net Liability For Unpaid Claims And Claims Adjustment Expense, Assumed Business, Net Reinsurance premium receivable Reinsurance Premiums Receivable Reinsurance Premiums Receivable Deferred charge Approximate value of additional funds transferred to trust Funds Transferred Under Reinsurance Agreements Reinsurance additional funds transferred. Limited parental guarantee obligations, initial amount (up to) Guarantor Obligations, Maximum Exposure, Undiscounted Percentage of reinsurance agreements entered Reinsurance Agreement, Percentage of Portfolios Percentage of reinsurance agreement entered. Reinsurance premium assumed Funds held by reinsured companies Total Funds Held Under Reinsurance Agreements Total Funds Held Under Reinsurance Agreements Total assets and liabilities assumed Asset Acquisition, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Asset Acquisition, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Number of agreements entered Reinsurance Agreement, Number Of Agreements Entered Reinsurance Agreement, Number Of Agreements Entered Number of reinsurance collateral trusts Number Of Reinsurance Collateral Trust Number of reinsurance collateral trust. Summary of Statutory Capital and Surplus Statutory Accounting Practices Disclosure [Table Text Block] Short-duration Insurance Contracts, Claims Development [Table] Short-duration Insurance Contracts, Claims Development [Table] Short-duration Insurance Contracts, Accident Year [Axis] Short-duration Insurance Contracts, Accident Year [Axis] Short-duration Insurance Contracts, Accident Year [Domain] Short-duration Insurance Contracts, Accident Year [Domain] Accident Year - 2007 Short-duration Insurance Contracts, Accident Year 2007 [Member] Accident Year - 2008 Short-duration Insurance Contracts, Accident Year 2008 [Member] Accident Year - 2009 Short-duration Insurance Contracts, Accident Year 2009 [Member] Accident Year - 2010 Short-duration Insurance Contracts, Accident Year 2010 [Member] Accident Year - 2011 Short-duration Insurance Contracts, Accident Year 2011 [Member] Accident Year - 2012 Short-duration Insurance Contracts, Accident Year 2012 [Member] Accident Year - 2013 Short-duration Insurance Contracts, Accident Year 2013 [Member] Accident Year - 2014 Short-duration Insurance Contracts, Accident Year 2014 [Member] Accident Year - 2015 Short-duration Insurance Contracts, Accident Year 2015 [Member] Accident Year - 2016 Short-duration Insurance Contracts, Accident Year 2016 [Member] Claims Development [Line Items] Claims Development [Line Items] Unpaid reported losses and allocated loss adjustment expenses, net of reinsurance Short-duration Insurance Contracts, Unpaid Reported Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance Short-duration Insurance Contracts, Unpaid Reported Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance IBNR losses and loss expenses, net of reinsurance Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net IBNR losses and loss expenses, net of reinsurance - assumed business Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net, Assumed Business Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net, Assumed Business Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net [Abstract] Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net [Abstract] Incurred losses and allocated loss adjustment expenses, net of reinsurance Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net All outstanding liabilities for unpaid losses and LAE prior to 2007, net of reinsurance Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented Total outstanding liabilities for unpaid losses and LAE, net of reinsurance Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net Cumulative number of reported claims Short-duration Insurance Contracts, Number of Reported Claims Unaudited Condensed Quarterly Financial Data Quarterly Financial Information [Text Block] Eagle Point Credit and PRIMA Capital Advisors Eagle Point Credit and PRIMA Capital Advisors [Member] Eagle Point Credit and PRIMA Capital Advisors Sound Point Capital Sound Point Capital [Member] Sound Point Capital [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Fund Investments Fund Investments [Member] Fund Investments [Member] Registered Investment Company Registered Investment Company [Member] Registered Investment Company [Member] Management fees Management Fee [Member] Management Fee [Member] Voting ordinary shares acquired (shares) Related Party Transaction Shares Acquired from Related Party Related Party Transaction Shares Acquired from Related Party Voting ordinary shares acquired, percent Related Party Transactions Percentage Of Equity Interest Acquired Related Party Transactions Percentage Of Equity Interest Acquired Number of newly elected board of directors Related Party Transaction, Number of Newly Elected Board of Directors Related Party Transaction, Number of Newly Elected Board of Directors Number of general partners Related Party Transaction, Number of General Partners Related Party Transaction, Number of General Partners Agreement period Related Party Transaction, Agreement period Related Party Transaction, Agreement period Redeemable noncontrolling interest, redemption period one Redeemable Noncontrolling Interest, Redemption Period One Redeemable Noncontrolling Interest, Redemption Period One Redeemable noncontrolling interest, redemption period two Redeemable Noncontrolling Interest, Redemption Period Two Redeemable Noncontrolling Interest, Redemption Period Two Redeemable noncontrolling interest Investment in registered investment company Interest income Interest Income, Related Party Separate account assets Separate Account Assets Management fees Related Party Transaction, Expenses from Transactions with Related Party Number of invested funds Number Of Investments Number Of Investments Estimated Fair Values of Investments in Fixed Maturity Investments, Short-Term Investments and Equities, Trading Securities Trading Securities [Table Text Block] Summary of Amortized Cost and Estimated Fair Value of Fixed Maturity and Short-term Investments by Contractual Maturity Investments Classified by Contractual Maturity Date [Table Text Block] Amortized Cost and Estimated Fair Values of Company's Fixed Maturity and Short-Term Investments Classified as Available-for-Sale Available-for-sale Securities [Table Text Block] Summary of Investments Classified as Available-for-Sale in Unrealized Loss Position as Well as Aggregate Fair Value and Gross Unrealized Loss by Length of Time Schedule of Unrealized Loss on Investments [Table Text Block] Credit Ratings Company's Fixed Maturity and Short-Term Investments Available-for-Sale Schedule Of Investments by Credit Rating [Table Text Block] Schedule Of Investments by Credit Rating Other Investments Other Investments [Table Text Block] [Table Text Block] for Other Investments Schedule of Life Settlement Contracts, Investment Method Schedule of Life Settlement Contracts, Investment Method [Table Text Block] Realized Gain (Loss) on Investments Realized Gain (Loss) on Investments [Table Text Block] Unrealized Gain (Loss) on Investments Unrealized Gain (Loss) on Investments [Table Text Block] Major Categories of Net Investment Income Investment Income [Table Text Block] Schedule of Carrying Value of Restricted Investments Schedule of Restricted Assets [Table Text Block] Schedule of Restricted Assets [Table Text Block] Condensed Income Statement [Table] Condensed Income Statement [Table] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Dividend income from subsidiaries Dividend Income From Subsidiaries Dividend Income From Subsidiaries EXPENSES Operating Expenses [Abstract] EARNINGS (LOSS) BEFORE EQUITY IN UNDISTRIBUTED EARNINGS OF SUBSIDIARIES Income (Loss) From Continuing Operations Before Income Taxes And Income (Loss) From Subsidiaries Income (Loss) from Continuing Operations Before Income Taxes and Income (Loss) from Subsidiaries EQUITY IN UNDISTRIBUTED EARNINGS OF SUBSIDIARIES - CONTINUING OPERATIONS Income (Loss) from Subsidiaries, Net of Tax, Continuing Operations Income (Loss) from Subsidiaries, Net of Tax, Continuing Operations EQUITY IN UNDISTRIBUTED EARNINGS OF SUBSIDIARIES - DISCONTINUING OPERATIONS Income (Loss) from Subsidiaries, Net of Tax, Discontinued Operations Income (Loss) from Subsidiaries, Net of Tax, Discontinued Operations Held-For-Sale Business Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Restricted Shares and Restricted Share Units Schedule of Nonvested Share Activity [Table Text Block] Summary of SARs Activity Schedule of Share-based Compensation, Stock Appreciation Rights Award Activity [Table Text Block] Assumptions Used to Estimate Fair Value of SARs Using Black-Scholes Option Valuation Model Schedule of Share-based Payment Award, Stock Appreciation Rights Award, Valuation Assumptions [Table Text Block] Schedule of Share-based Payment Award, Stock Appreciation Rights Award, Valuation Assumptions [Table Text Block] Condensed Financial Statements [Table] Condensed Financial Statements [Table] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Interest paid Interest Paid Dividends and return of capital from subsidiaries, non-cash Dividends and Return of Capital from Subsidiaries, Non-Cash Dividends and Return of Capital from Subsidiaries, Non-Cash Contributions to subsidiaries, non-cash Contributions To Subsidiaries, Non-Cash Contributions To Subsidiaries, Non-Cash Increase in retained earnings Increase (Decrease) in Retained Earnings (Accumulated Deficit) Increase (Decrease) in Retained Earnings (Accumulated Deficit) Net earnings attributable to Enstar Group Limited Significant New Business Significant New Business [Text Block] Significant new business. Funds held - directly managed, carrying value Funds Held under Reinsurance Agreements, Directly Managed, Carrying Value Funds Held under Reinsurance Agreements, Directly Managed, Carrying Value Funds held - directly managed, embedded derivative, fair value Funds Held under Reinsurance Agreements, Directly Managed, Fair Value of Embedded Derivative, Net Funds Held under Reinsurance Agreements, Directly Managed, Fair Value of Embedded Derivative, Net Funds held - directly managed Total Losses and Loss Adjustment Expense Liabilities, and Reconciliation of Beginning and Ending Balances Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Schedule of Incurred Losses Schedule of Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Schedule of Gross and Net Losses and LAE Reserves by Category Schedule of Liability for Claims and Claims Adjustment Expense by Category [Table Text Block] Schedule of Liability for Claims and Claims Adjustment Expense by Category [Table Text Block] Incurred and Paid Loss Development Information, and IBNR Liabilities and Cumulative Loss Frequency Short-duration Insurance Contracts, Claims Development [Table Text Block] Reconciliation of Incurred and Paid Loss Development to Liability for Unpaid Losses and LAE Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Table Text Block] Average Annual Duration of Claims Short-duration Insurance Contracts, Schedule of Historical Claims Duration [Table Text Block] PREMIUMS WRITTEN AND EARNED Reinsurance [Text Block] Numerator: Net Income (Loss) Attributable to Parent [Abstract] Net earnings from continuing operations Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Net earnings (losses) from discontinuing operations Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Restricted shares Restricted Stock [Member] Restricted share units Restricted Stock Units (RSUs) [Member] Effect of dilutive securities: Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Shares (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Warrants (in shares) Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants Preferred shares (shares) Incremental Common Shares Attributable to Dilutive Effect of Conversion of Preferred Stock Weighted average ordinary shares outstanding - diluted (shares) Basic: Diluted: Losses and Loss Adjustment Expenses Line of Credit Facility [Table] Line of Credit Facility [Table] Sussex Facility Sussex Facility [Member] Sussex Facility [Member] EGL Term Loan Facility EGL Term Loan Facility [Member] EGL Term Loan Facility [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Term Debt Instrument, Term Total loans payable Life and Annuities Segment Non-life Run-off Segment ASSETS Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract] Trading, at fair value Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Trading Securities, Debt Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Trading Securities, Debt Available-for-sale, at fair value Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Available-For-Sale-Securities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Available-for-sale Securities Equities, trading, at fair value Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Trading Securities, Equity Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Trading Securities, Equity Other investments, at fair value Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Investments Business combination recognized identifiable assets acquired and liabilities assumed other investments. Total investments Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Investments Business combination recognized identifiable assets acquired and liabilities assumed investments. Cash and cash equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Restricted cash and cash equivalents Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Restricted Cash And Cash Equivalents Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Restricted Cash And Cash Equivalents Accrued interest receivable Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Interest Receivable Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Interest Receivable Premiums receivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premiums Receivable At Carrying Value Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premiums Receivable At Carrying Value Reinsurance balances recoverable Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Reinsurance Recoverables On Paid And Unpaid Losses Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Reinsurance Recoverables On Paid And Unpaid Losses Reinsurance balances recoverable — reserves Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Reinsurance Recoverables Reserves Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Reinsurance Recoverables Reserves Reinsurance balances recoverable — paids Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Reinsurance Recoverables Paid Claims Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Reinsurance Recoverables Paid Claims Prepaid reinsurance premiums Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Prepaid Reinsurance Premiums Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Prepaid Reinsurance Premiums Intangible assets Other assets Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Assets Business combination recognized identifiable assets acquired and liabilities assumed other assets. TOTAL ASSETS Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets LIABILITIES Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract] Losses and LAE Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liability for Claims and Claims Adjustment Expense Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liability for Claims and Claims Adjustment Expense Funds withheld Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Funds Withheld As Liabilities Business combination recognized identifiable assets acquired and liabilities assumed funds withheld as liabilities. Insurance and reinsurance balances payable Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Reinsurance Payable Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Reinsurance Payable Unearned premium Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Unearned Premiums Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Unearned Premiums Other liabilities - Asbestos related Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Asbestos Liabilities Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Asbestos Liabilities Other liabilities Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Liabilities Business combination recognized identifiable assets acquired and liabilities assumed other liabilities. TOTAL LIABILITIES Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities NET ASSETS ACQUIRED AT FAIR VALUE ACQUISITION DATE FAIR VALUE Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Summary of Operations by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of Revenue from External Customers Revenue from External Customers by Geographic Areas [Table Text Block] Summary of Company's Assets by Segment Reconciliation of Assets from Segment to Consolidated [Table Text Block] Valuation and Qualifying Accounts [Abstract] Valuation and Qualifying Accounts Disclosure [Table] Valuation and Qualifying Accounts Disclosure [Table] Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves [Domain] Valuation Allowances and Reserves [Domain] Reinsurance balances recoverable, provisions for bad debt Allowance for Reinsurance Recoverable [Member] Valuation allowance for deferred tax assets Valuation Allowance of Deferred Tax Assets [Member] Valuation and Qualifying Accounts Disclosure [Line Items] Valuation and Qualifying Accounts Disclosure [Line Items] Movement in Valuation Allowances and Reserves [Roll Forward] Movement in Valuation Allowances and Reserves [Roll Forward] Balance at Beginning of Year Valuation Allowances and Reserves, Balance Charged to costs and expenses Valuation Allowances and Reserves, Additions for Charges to Cost and Expense Charged to other accounts Valuation Allowances and Reserves, Additions for Charges to Other Accounts Deductions Valuation Allowances and Reserves, Deductions Balance at End of Year Condensed Statement of Comprehensive Income [Table] Condensed Statement of Comprehensive Income [Table] Condensed Statement of Income Captions [Line Items] Condensed Statement of Income Captions [Line Items] NET EARNINGS OTHER COMPREHENSIVE INCOME (LOSS) RELATING TO SUBSIDIARIES, NET OF TAX Comprehensive Income (Loss) from Subsidiaries, Net of Tax Comprehensive Income (Loss) from Subsidiaries, Net of Tax COMPREHENSIVE INCOME ATTRIBUTABLE TO ENSTAR GROUP LIMITED Comprehensive Income (Loss), Net of Tax, Attributable to Parent Schedule IV - Reinsurance Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Text Block] Performance Target [Axis] Performance Target [Axis] Performance Target [Axis] Performance Target [Domain] Performance Target [Domain] [Domain] for Performance Target [Axis] Performance Target One Performance Target One [Member] Performance Target One [Member] Performance Target Two Performance Target Two [Member] Performance Target Two [Member] Performance Target Three Performance Target Three [Member] Performance Target Three [Member] Performance share units Performance Shares [Member] Number of shares, granted (shares) Grant date fair value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Grant Date Fair Value Percentage increase in fully diluted book value per share Share-based Compensation Arrangement by Share-based Payment Award, Performance Calculation, Percent Increase In Fully Diluted Book Value Share-based Compensation Arrangement by Share-based Payment Award, Performance Calculation, Percent Increase In Fully Diluted Book Value Share settlement percentage Share-based Compensation Arrangement by Share-based Payment Award, Performance Calculation, Share Settlement Percentage Share-based Compensation Arrangement by Share-based Payment Award, Performance Calculation, Share Settlement Percentage Acquisitions Business Combination Disclosure [Text Block] Domestic (Bermuda) Income (Loss) from Continuing Operations before Income Taxes, Domestic Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Prior Period Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense, Prior Years [Abstract] Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense, Prior Years [Abstract] Current Period Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense, Current Year [Abstract] Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense, Current Year [Abstract] Net losses paid, current period Net change in case and LAE reserves, current period Change in Case and Loss Adjustment Expense Reserve Period Increase (Decrease), Current Year Change in Case and Loss Adjustment Expense Reserve Period Increase (Decrease), Current Year Net change in IBNR reserves, current period Liability For Unpaid Claims And Claims Adjustment Expense, Incurred But Not Reported Claims Amount, Period Increase (Decrease), Current Year Liability For Unpaid Claims And Claims Adjustment Expense, Incurred But Not Reported Claims Amount, Period Increase (Decrease), Current Year Amortization of deferred charges, current period Deferred Costs, Current And Noncurrent, Amortization, Current Year Deferred Costs, Current And Noncurrent, Amortization, Current Year Increase (reduction) in estimates of net ultimate losses, current period Estimates of Net Ultimate Losses, Period Increase (Decrease), Current Year Estimates of Net Ultimate Losses, Period Increase (Decrease), Current Year Increase (reduction) in provisions for bad debt, current period Provision For Doubtful Accounts, Current Year Provision For Doubtful Accounts, Current Year Increase (reduction) in provisions for unallocated LAE, current period Provision For Unallocated Claim Adjustment Expense, Current Year Provision For Unallocated Claim Adjustment Expense, Current Year Amortization of fair value adjustments, current period Claims And Claims Adjustment Expense, Amortization Of Fair Value Adjustments, Current Year Claims And Claims Adjustment Expense, Amortization Of Fair Value Adjustments, Current Year Total Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract] Net losses paid Net change in case and LAE reserves Change in Case and Loss Adjustment Expense Reserve Period Increase (Decrease) Change in Case and Loss Adjustment Expense Reserve Period Increase (Decrease) Net change in IBNR reserves Liability For Unpaid Claims And Claims Adjustment Expense, Incurred But Not Reported Claims Amount, Period Increase (Decrease) Liability For Unpaid Claims And Claims Adjustment Expense, Incurred But Not Reported Claims Amount, Period Increase (Decrease) Amortization of deferred charges Increase (reduction) in estimates of net ultimate losses Estimates of Net Ultimate Losses, Period Increase (Decrease) Estimates of Net Ultimate Losses, Period Increase (Decrease) Increase (reduction) in provisions for bad debt Provision for Doubtful Accounts Increase (reduction) in provisions for unallocated LAE Provision For Unallocated Claim Adjustment Expense Provision For Unallocated Claim Adjustment Expense Amortization of fair value adjustments Claims And Claims Adjustment Expense, Amortization Of Fair Value Adjustments Claims And Claims Adjustment Expense, Amortization Of Fair Value Adjustments Wilton Re Wilton Re [Member] Wilton Re [Member] CPPIB and Management of Wilton Re Canada Pension Plan Investment Board and Management of Wilton Re [Member] Canada Pension Plan Investment Board and Management of Wilton Re [Member] CPPIB Epsilon Ontario Limited Partnership CPPIB Epsilon Ontario Limited Partnership [Member] CPPIB Epsilon Ontario Limited Partnership [Member] Reinsurance balances recoverable Reinsurance Recoverables, Including Reinsurance Premium Paid Statement of Cash Flows [Abstract] Net earnings Net (earnings) loss from discontinued operations Adjustments to reconcile net earnings to cash flows provided by (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Realized losses (gains) on sale of investments Marketable Securities, Realized Gain (Loss) Unrealized losses (gains) on investments Unrealized Gain (Loss) on Marketable Securities, Cost Method Investments, and Other Investments Other non-cash items Other Noncash Income (Expense) Depreciation and other amortization Depreciation, Depletion and Amortization Net change in trading securities held on behalf of policyholders Net Change in Trading Securities Held on Behalf of Policyholders Net Change in Trading Securities Held on Behalf of Policyholders Sales and maturities of trading securities Proceeds from Sale of Securities, Operating Activities Purchases of trading securities Payments for Purchase of Securities, Operating Activities Changes in: Increase (Decrease) in Operating Capital [Abstract] Reinsurance balances recoverable Increase (Decrease) in Reinsurance Recoverable Funds held by reinsured companies Increase (Decrease) in Funds Held under Reinsurance Agreements Losses and loss adjustment expenses Increase (Decrease) in Liability for Claims and Claims Adjustment Expense Reserve Policy benefits for life and annuity contracts Increase (Decrease) in Life Insurance Liabilities Insurance and reinsurance balances payable Increase (Decrease) in Reinsurance Payables Unearned premiums Increase (Decrease) in Unearned Premiums Other operating assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash flows provided by (used in) operating activities Acquisitions, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Sales and maturities of available-for-sale securities Proceeds from Sale and Maturity of Available-for-sale Securities Purchase of available-for-sale securities Payments to Acquire Available-for-sale Securities Purchase of other investments Payments to Acquire Other Investments Redemption of other investments Proceeds from Sale and Maturity of Other Investments Other investing activities Payments for (Proceeds from) Other Investing Activities Distribution of capital to noncontrolling interest Payments to Noncontrolling Interests Contribution by redeemable noncontrolling interest Proceeds from Noncontrolling Interests Contribution by redeemable noncontrolling interest Proceeds from Redeemable Noncontrolling Interest Proceeds from Redeemable Noncontrolling Interest Dividends paid to noncontrolling interest Payments of Ordinary Dividends, Noncontrolling Interest Purchase of noncontrolling interest Payments for Repurchase of Redeemable Noncontrolling Interest EFFECT OF EXCHANGE RATE CHANGES ON FOREIGN CURRENCY CASH, CASH EQUIVALENTS AND RESTRICTED CASH Effect Of Exchange Rate On Cash, Cash Equivalents, Restricted Cash And Restricted Cash Equivalents Effect Of Exchange Rate On Cash, Cash Equivalents, Restricted Cash And Restricted Cash Equivalents NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH Cash, Cash Equivalents, Restricted Cash And Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, Cash Equivalents, Restricted Cash And Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF YEAR Cash, Cash Equivalents, Restricted Cash And Restricted Cash Equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF YEAR Supplemental Cash Flow Information: Supplemental Cash Flow Information [Abstract] Income taxes paid, net of refunds Income Taxes Paid, Net Reconciliation to Consolidated Balance Sheets: Cash, Cash Equivalents, Restricted Cash And Restricted Cash Equivalents, Including Disposal Group And Discontinued Operations [Abstract] Cash, Cash Equivalents, Restricted Cash And Restricted Cash Equivalents, Including Disposal Group And Discontinued Operations [Abstract] Restricted cash and cash equivalents Restricted Cash and Cash Equivalents Cash, cash equivalents and restricted cash Summary of Reinsurance Reserves Recoverable Effects of Reinsurance [Table Text Block] Reinsurance Balances Recoverable by Reinsurer Ceded Credit Risk [Table Text Block] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Series B non-voting convertible ordinary shares Common Class B [Member] Series D non-voting convertible ordinary shares Common Class D [Member] Common Class D [Member] Non-voting ordinary shares Nonvoting Common Stock [Member] Series B non-voting preferred shares Series B Preferred Stock [Member] Class of Stock [Line Items] Class of Stock [Line Items] Common shares, authorized (shares) Common Stock, Shares Authorized Preference shares, authorized (shares) Preferred Stock, Shares Authorized Common stock, number of votes Common Stock, Voting Rights, Number Of Votes Common Stock, Voting Rights, Number Of Votes Percentage ownership (or more) of voting ordinary shares entitled to less than one vote per share Common Stock, Voting Rights, Ownership Percentage Entitled To Less Than One Vote Common Stock, Voting Rights, Ownership Percentage Entitled To Less Than One Vote Conversion ratio, issued upon conversion (shares) Convertible Common Stock, Shares Issued Upon Conversion Convertible Common Stock, Shares Issued Upon Conversion Aggregate voting power of Company's issued share capital (percent) (not to exceed) Common Stock, Voting Rights, Percentage Aggregate Voting Power May Not Exceed Common Stock, Voting Rights, Percentage Aggregate Voting Power May Not Exceed Ordinary shares, issued (shares) Conversion of stock, shares converted (shares) Conversion of Stock, Shares Converted Warrants outstanding (shares) Warrants exercised (shares) Class of Warrant or Right, Warrants Exercised Class of Warrant or Right, Warrants Exercised Stock issued upon exercise of Warrants (shares) Stock Issued During Period, Shares, Warrant Exercised Stock Issued During Period, Shares, Warrant Exercised Stock issued upon conversion (shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Preferred shares, liquidation preference (dollars per share) Preferred Stock, Liquidation Preference Per Share Issuance of stock (shares) Stock Issued During Period, Shares, New Issues Repayment of loans Interest expense Interest Expense, Debt Facility term Number of financial institutions Debt Instrument, Number of Financial Institutions Debt Instrument, Number of Financial Institutions Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Optional additional commitment Line of Credit Facility, Optional Additional Borrowing Capacity Line of Credit Facility, Optional Additional Borrowing Capacity Available unutilized capacity Line of Credit Facility, Remaining Borrowing Capacity Frequency of interest payments (at least) Line Of Credit Facility, Interest Payment Period Line Of Credit Facility, Interest Payment Period Covenant compliance, consolidated indebtedness to total capitalization (not greater than) Line Of Credit Facility, Covenant Compliance, Consolidated Indebtedness To Total Capitalization Ratio Line Of Credit Facility, Covenant Compliance, Consolidated Indebtedness To Total Capitalization Ratio Covenant compliance, net income (loss) threshold Line Of Credit Facility, Covenant Compliance, Consolidated Tangible Net Worth Calculation, Minimum Line Of Credit Facility, Covenant Compliance, Consolidated Tangible Net Worth Calculation, Minimum Covenant compliance, net income threshold percent Line Of Credit Facility, Covenant Compliance, Consolidated Tangible Net Worth Calculation, Net Income Percentage Line Of Credit Facility, Covenant Compliance, Consolidated Tangible Net Worth Calculation, Net Income Percentage Covenant compliance, percentage of proceeds of common stock issuance Line Of Credit Facility, Covenant Compliance, Consolidated Tangible Net Worth Calculation, Proceeds From Issuance of Common Stock Percentage Line Of Credit Facility, Covenant Compliance, Consolidated Tangible Net Worth Calculation, Proceeds From Issuance of Common Stock Percentage Currency translation gain (loss) Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Percentage of consideration payable for acquisition Line of Credit Facility, Percentage of Consideration Payable Funded through Proceeds Line of Credit Facility, Percentage of Consideration Payable Funded through Proceeds Debt instrument, covenant compliance, statutory surplus threshold, multiplier Line Of Credit Facility, Covenant Compliance, Statutory Surplus Threshold Multiplier Line Of Credit Facility, Covenant Compliance, Statutory Surplus Threshold Multiplier Debt instrument, covenant compliance, outstanding loan balance threshold, multiplier Line Of Credit Facility, Covenant Compliance, Outstanding Loan Balance Threshold Multiplier Line Of Credit Facility, Covenant Compliance, Outstanding Loan Balance Threshold Multiplier Debt instrument, covenant compliance, capital resources multiplier for solvency requirements Debt Instrument, Covenant Compliance, Capital Resources Multiplier To Meet Minimum Solvency Requirement Debt Instrument, Covenant Compliance, Capital Resources Multiplier To Meet Minimum Solvency Requirement Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Ceded Credit Risk [Table] Ceded Credit Risk [Table] Ceded Credit Risk, Reinsurer [Axis] Ceded Credit Risk, Reinsurer [Axis] Ceded Credit Risk, Reinsurer [Domain] Ceded Credit Risk, Reinsurer [Domain] Top Ten Reinsurers Top Ten Reinsurers [Member] Top ten reinsurers. Other Reinsurers' Balances Greater Than $1 Million Other Reinsurers Balances Greater Than One Million Dollars [Member] Other reinsurers balances greater than one million dollars. Other Reinsurers' Balances Less Than $1 Million Other Reinsurers Balances Less Than One Million Dollars [Member] Other reinsurers balances less than one million dollars. Ceded Credit Risk [Line Items] Ceded Credit Risk [Line Items] Reinsurance balances recoverable Sale of entities, consideration Disposal Group, Including Discontinued Operation, Consideration Restricted investments Disposal Group, Including Discontinued Operation, Restricted Investments Disposal Group, Including Discontinued Operation, Restricted Investments Cumulative translation adjustment balance in accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Categorized Investments Recorded at Fair Value among Levels Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table Text Block] Reconciliation of Beginning and Ending Balances for All Investments Measured at Fair Value on Recurring Basis Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Basis of Preparation Basis of Accounting, Policy [Policy Text Block] Basis of Consolidation Consolidation, Policy [Policy Text Block] Reclassifications Reclassification, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Premiums Insurance Premiums Revenue Recognition, Policy [Policy Text Block] Acquisition Costs Deferred Policy Acquisition Costs, Policy [Policy Text Block] Losses and LAE Unpaid Policy Claims and Claims Adjustment Expense, Policy [Policy Text Block] Policy Benefits for Life and Annuity Contracts Future Policy Benefits Liability, Policy [Policy Text Block] Reinsurance Recoverable Reinsurance Accounting Policy [Policy Text Block] Investments Investment, Policy [Policy Text Block] Cash and cash equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Fees and Commission Income Revenue Recognition, Services, Commissions [Policy Text Block] Foreign Exchange Foreign Currency Transactions and Translations Policy [Policy Text Block] Share-based Compensation Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Derivative Instruments Derivatives, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Acquisitions Business Combinations Policy [Policy Text Block] Acquisitions, Fair Value Adjustment Intangible Assets Arising from Insurance Contracts Acquired in Business Combination, Policy [Policy Text Block] Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Intangible Assets Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Retroactive Reinsurance and Deferred Charges Deferred Charges, Policy [Policy Text Block] Redeemable Noncontrolling Interest Redeemable Noncontrolling Interests Policy [Text Block] Redeemable Noncontrolling Interests Policy [Text Block] Internal-use Software Internal Use Software, Policy [Policy Text Block] Held-for-sale Business and Discontinued Operations Discontinued Operations, Policy [Policy Text Block] New Accounting Standards Adopted and Recently Issued Accounting Pronouncements Not Yet Adopted New Accounting Pronouncements, Policy [Policy Text Block] Schedule I - Summary of Investments Other Than Investments in Related Parties Summary of Investments, Other than Investments in Related Parties [Text Block] Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Tax Credit Carryforward [Axis] Tax Credit Carryforward [Axis] Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Capital loss carryforward Capital Loss Carryforward [Member] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Foreign Tax Authority Foreign Tax Authority [Member] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Domain] Income Tax Authority, Name [Domain] United States Internal Revenue Service (IRS) [Member] United Kingdom Her Majesty's Revenue and Customs (HMRC) [Member] Other Other Income Tax Authority [Member] Other Income Tax Authority [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Operating loss carryforward Operating Loss Carryforwards Tax credit carryforward Tax Credit Carryforward, Amount Tax effect of operating loss carryforward Deferred Tax Assets, Operating Loss Carryforwards Tax effect of capital loss carryforward Deferred Tax Assets, Capital Loss Carryforwards Tax effect of alternative minimum tax credit Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax Foreign Currency Forward Exchange Contracts Schedule of Derivative Instruments [Table Text Block] Collateral in trust for third party agreements Assets Held-in-trust Assets on deposit with regulatory authorities Deposit Assets Assets on deposit with regulatory authorities Trading Securities Pledged as Collateral Funds at Lloyd's Funds in Syndicate Funds in Syndicate Restricted assets, total Restricted Cash and Investments Number of syndicates Restricted Cash and Investments, Number of Syndicates Restricted Cash and Investments, Number of Syndicates Cash and investments Funds in Syndicate, Cash and Investments Funds in Syndicate, Cash and Investments FAL Facility FAL Facility [Member] FAL Facility [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Letters of Credit Letter of Credit [Member] Higher borrowing capacity option Line of Credit Facility, Higher Borrowing Capacity Option Line of Credit Facility, Higher Borrowing Capacity Option Dividend Restrictions and Statutory Financial Information Insurance Disclosure [Text Block] Amortized Cost Funds Held, Directly Managed, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract] Funds Held, Directly Managed, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract] Fair Value Funds Held, Directly Managed, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract] Funds Held, Directly Managed, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract] % of Total Fair Value Funds Held, Directly Managed, Debt Maturities, Fair Value, Fiscal Year Maturity, Percent [Abstract] Funds Held, Directly Managed, Debt Maturities, Fair Value, Fiscal Year Maturity, Percent [Abstract] Schedule of Deferred Compensation Arrangement with Individual, Share-based Payments [Table] Schedule of Deferred Compensation Arrangement with Individual, Share-based Payments [Table] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Long-term incentive plans Long Term Incentive Plans [Member] Long Term Incentive Plans [Member] Deferred compensation plan Deferred Compensation Plan [Member] Deferred Compensation Plan [Member] Previous deferred compensation plan Previous Deferred Compensation Plan [Member] Previous Deferred Compensation Plan [Member] Employee share purchase plan Employee Stock Purchase Plan [Member] Employee stock purchase plan. Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Director Director [Member] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Domain] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Domain] Time-based restricted shares Time-Based Restricted Stock [Member] Time-Based Restricted Stock [Member] Employee stock Employee Stock [Member] Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] Restricted share units credited to the accounts of non-employee directors (shares) Deferred Compensation Arrangement with Individual, Shares Issued Expenses related to the restricted share units Deferred Compensation Arrangement with Individual, Compensation Expense Deferred compensation arrangement, shares converted Deferred Compensation Arrangement With Individual, Shares Converted Deferred Compensation Arrangement With Individual, Shares Converted Number of directors Deferred Compensation Arrangement With Individual, Number of Individuals Converted Shares Deferred Compensation Arrangement With Individual, Number of Individuals Converted Shares Stock issued to employees (shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Schedule of Gain (Loss) on Investments [Table] Schedule of Gain (Loss) on Investments [Table] Fixed maturity investments Debt Securities [Member] Gain (Loss) on Investments [Line Items] Gain (Loss) on Investments [Line Items] Gross realized gains on fixed maturity securities, available-for-sale Available-for-sale Securities, Gross Realized Gains Gross realized (losses) on fixed maturity securities, available-for-sale Available-for-sale Securities, Gross Realized Losses Net realized gains (losses) on trading securities Trading Securities, Realized Gain (Loss) Total net realized gains (losses) on sale Gain (Loss) on Sale of Investments Net unrealized gains (losses) on trading securities Trading Securities, Change in Unrealized Holding Gain (Loss) Change in fair value of embedded derivative Unrealized Gain (Loss) on Investments Change in fair value of embedded derivative on funds held – directly managed Gain (Loss) on Embedded Derivative on Funds Held Directly Managed Gain (Loss) on Embedded Derivative on Funds Held Directly Managed Total net unrealized gains (losses) Marketable Securities, Unrealized Gain (Loss) Net realized gains (losses) and change in fair value of embedded derivative Proceeds from sales of available-for-sale securities Proceeds from Sale of Available-for-sale Securities Hastings companies Hastings Companies [Member] Hastings Companies [Member] Goldman Sachs affiliates Goldman Sachs Affiliates [Member] Goldman Sachs Affiliates [Member] Goldman Sachs Goldman Sachs Co [Member] Goldman Sachs Co [Member] Hastings Insurance Group Limited Hastings Insurance Group Limited [Member] Hastings Insurance Group Limited [Member] Indirect non-voting investments in number of companies Related Party Transaction, Investments, Number of Affiliated Companies Related Party Transaction, Investments, Number of Affiliated Companies Investment in indirect non-voting interests of affiliated companies Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Ceded Credit Risk, Collateralization [Axis] Ceded Credit Risk, Collateralization [Axis] Ceded Credit Risk, Collateralization [Domain] Ceded Credit Risk, Collateralization [Domain] Secured Ceded Credit Risk, Secured [Member] Unsecured Ceded Credit Risk, Unsecured [Member] Reinsurers rated A- or above Reinsurers Rated A Minus Or Above [Member] Reinsurers rated A minus or above. Reinsurers Rated Below A- Reinsurers Rated Below A Minus [Member] Reinsurers Rated Below A Minus [Member] Credit Rating, Standard & Poor's [Axis] Credit Rating, Standard & Poor's [Axis] External Credit Rating, Standard & Poor's [Domain] External Credit Rating, Standard & Poor's [Domain] Gross Reinsurance Recoverables, Gross Provisions for Bad Debt Reinsurance Recoverables, Allowance Provisions as a % of Gross Percentage of Reinsurance Recoverables Allowance to Reinsurance Recoverables Gross Percentage of Reinsurance Recoverables Allowance to Reinsurance Recoverables Gross Outstanding losses Liability for Unpaid Claims and Claims Adjustment Expense, Reported Claims, Amount IBNR Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount Fair value adjustments Liability For Claims And Claims Adjustment Expense, Fair Value Adjustments Liability For Claims And Claims Adjustment Expense, Fair Value Adjustments Total gross liability for unpaid losses and LAE Credit Rating, Standard And Poor's, Fitch [Axis] Credit Rating, Standard And Poor's, Fitch [Axis] Credit Rating, Standard And Poor's, Fitch [Axis] Credit Rating, Standard And Poor's, Fitch [Domain] Credit Rating, Standard And Poor's, Fitch [Domain] Credit Rating, Standard And Poor's, Fitch AAA Rated Standard & Poor's, Fitch, AAA Rating Member [Member] Standard & Poor's, Fitch, AAA Rating Member AA Rated Standard & Poor's, Fitch, AA Rating [Member] Standard & Poor's, Fitch, AA Rating [Member] A Rated Standard & Poor's, Fitch, A Rating [Member] Standard & Poor's, Fitch, A Rating [Member] BBB Rated Standard & Poor's, Fitch, BBB Rating [Member] Standard & Poor's, Fitch, BBB Rating [Member] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Domain] External Credit Rating by Grouping [Domain] Investment Grade External Credit Rating, Investment Grade [Member] Portfolio Concentration Risk Member Portfolio Concentration Risk Member [Member] Portfolio Concentration Risk Member [Member] Credit Rating Concentration Risk Credit Rating Concentration Risk [Member] Credit Rating Concentration Risk [Member] Amortized Cost Fair Value % of Total Investments Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fixed Maturity Investments Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Beginning fair value Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Total realized and unrealized gains (losses) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Net transfers into (out of) Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net Ending fair value Fair Value, Assets and Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Fair Value, Assets and Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Fair Value, Assets and Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Beginning fair value Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs Purchases Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases Sales Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Sales Total realized and unrealized gains (losses) Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings Net transfers into (out of) Level 3 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers, Net Ending fair value Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Beginning fair value Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset Value And Net Derivative Asset (Liability) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value and Net Derivative Asset (Liability) Purchases Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset And Net Derivative Asset (Liability), Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset and Net Derivative Asset (Liability), Purchases Sales Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset And Net Derivative Asset (Liability), Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset and Net Derivative Asset (Liability), Sales Total realized and unrealized gains (losses) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset and Net Derivative Asset (Liability), Gain (Loss) Included in Earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset and Net Derivative Asset (Liability), Gain (Loss) Included in Earnings Net transfers into (out of) Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset and Net Derivative Asset (Liability), Transfers, Net Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset and Net Derivative Asset (Liability), Transfers, Net Ending fair value Noncontrolling Interest [Table] Noncontrolling Interest [Table] JCF II Funds JCF II Funds [Member] JCF II Funds [Member] Shinsei Shinsei Bank, Limited [Member] Shinsei Bank, Limited [Member] Noncontrolling Interest [Line Items] Noncontrolling Interest [Line Items] Noncontrolling interest Stockholders' Equity Attributable to Noncontrolling Interest Purchase of noncontrolling shareholders' interest in subsidiaries Related Party Transactions Related Party Transactions Disclosure [Text Block] Asbestos Asbestos Exposure [Member] Asbestos Exposure [Member] Environmental Environmental Exposure [Member] Environmental Exposure [Member] Workers' compensation/personal accident Marine, aviation and transit Marine, Aviation, and Transit Exposure [Member] Marine, Aviation, and Transit Exposure [Member] Construction defect Construction Defect Exposure [Member] Construction Defect Exposure [Member] Other Other Short-duration Insurance Product Line [Member] OLR, Gross Liability for Unpaid Claims and Claims Adjustment Expense, Reported Claims, Amount, Excluding Unallocated Liability for Unpaid Claims and Claims Adjustment Expense, Reported Claims, Amount, Excluding Unallocated IBNR, Gross Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount, Excluding Unallocated Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount, Excluding Unallocated Total, Gross Liability for Unpaid Claims and Claims Adjustment Expense, Excluding Accumulated Unallocated Claim Adjustment Expense Liability for Unpaid Claims and Claims Adjustment Expense, Excluding Accumulated Unallocated Claim Adjustment Expense OLR, Net Liability for Unpaid Claims and Claims Adjustment Expense, Reported Claims, Amount, Net, Excluding Unallocated Liability for Unpaid Claims and Claims Adjustment Expense, Reported Claims, Amount, Net, Excluding Unallocated IBNR, Net Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount, Net, Excluding Unallocated Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount, Net, Excluding Unallocated Total, Net Liability for Unpaid Claims and Claims Adjustment Expense, Net, Excluding Accumulated Unallocated Claim Adjustment Expense Liability for Unpaid Claims and Claims Adjustment Expense, Net, Excluding Accumulated Unallocated Claim Adjustment Expense Unallocated loss adjustment expenses Short-duration Insurance Contracts, Liability for Unpaid Claims and Claims Adjustment Expense, Accumulated Unallocated Claim Adjustment Expense Total, Net Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Lloyd’s syndicate capacity Lloyd's Syndicate Capacity [Member] Lloyd's Syndicate Capacity [Member] Licenses Licensing Agreements [Member] Management contract Contract-Based Intangible Assets [Member] Indefinite-lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Line Items] Intangible assets with an indefinite life, Carrying Value Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Losses and LAE liabilities Losses And Loss Adjustment Expense Liabilities [Member] Losses And Loss Adjustment Expense Liabilities [Member] Other Assets Fair Value Adjustment Intangible, Other Asset [Member] Fair Value Adjustment Intangible, Other Asset [Member] Other Liabilities Fair Value Adjustment Intangible, Other Liabilities [Member] Fair Value Adjustment Intangible, Other Liabilities [Member] Distribution channel Distribution Rights [Member] Technology Brand Trade Dress [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Gross Carrying Value, Fair value adjustments Intangible Assets Arising From Insurance Contracts Acquired In Business Combination, Gross Intangible Assets Arising From Insurance Contracts Acquired In Business Combination, Gross Accumulated Amortization, Fair value adjustments Intangible Assets Arising From Insurance Contracts Acquired In Business Combination, Accumulated Amortization Intangible Assets Arising From Insurance Contracts Acquired In Business Combination, Accumulated Amortization Net Carrying Value, Fair value adjustments Gross Carrying Value Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Intangible assets with a definite life, Net Carrying Value Deferred charge on retroactive reinsurance, Gross Carrying Value Deferred Costs Current And Noncurrent, Gross Deferred Costs Current And Noncurrent, Gross Deferred charge on retroactive reinsurance, Accumulated Amortization Deferred Costs Current And Noncurrent, Accumulated Amortization Deferred Costs Current And Noncurrent, Accumulated Amortization Deferred charge on retroactive reinsurance, Net Carrying Value Statement of Financial Position [Abstract] Trading, at fair value Available-for-sale, at fair value Available-for-sale Securities Total investments Investments Premiums receivable Premiums Receivable, Net Deferred tax assets Deferred Income Tax Assets, Net Prepaid reinsurance premiums Prepaid Reinsurance Premiums Deferred acquisition costs Deferred Policy Acquisition Costs Goodwill and intangible assets Assets held for sale Losses and loss adjustment expenses Policy benefits for life and annuity contracts Liability for Future Policy Benefits Unearned premiums Unearned Premiums Insurance and reinsurance balances payable Deferred tax liabilities Deferred Income Tax Liabilities, Net Liabilities held for sale COMMITMENTS AND CONTINGENCIES Commitments and Contingencies REDEEMABLE NONCONTROLLING INTEREST TOTAL SHAREHOLDERS’ EQUITY TOTAL LIABILITIES, REDEEMABLE NONCONTROLLING INTEREST AND SHAREHOLDERS’ EQUITY Goodwill, Intangible Assets and Deferred Charges Goodwill, Intangible Assets, Intangible Assets Arising from Insurance Contracts Acquired in Business Combination, and Deferred Charges Disclosure [Text Block] Goodwill, Intangible Assets, Intangible Assets Arising from Insurance Contracts Acquired in Business Combination, and Deferred Charges Disclosure [Text Block] Loans Payable Debt Disclosure [Text Block] Schedule of Trading Securities and Available-for-sale Securities [Table] Schedule of Trading Securities and Available-for-sale Securities [Table] Schedule of Trading Securities and Available-for-sale Securities [Table] Credit Rating, Standard And Poor's, Fitch [Axis] Not Rated Not Rated [Member] Not rated. Marketable Securities Member Marketable Securities Member [Member] Marketable Securities Member [Member] Trading and Available for Sale Securities Trading and Available for Sale Securities [Member] Trading and Available for Sale Securities [Member] Concentration Risk Type [Axis] External Credit Rating by Grouping [Axis] Non-Investment Grade External Credit Rating, Non Investment Grade [Member] Investments by Category [Axis] Trading Securities and Available for Sale Securities Trading Securities and Available for Sale Securities [Member] Trading Securities and Available for Sale Securities [Member] Schedule of Trading Securities and Available-for-sale Securities [Line Items] Schedule of Trading Securities and Available-for-sale Securities [Line Items] [Line Items] for Schedule of Trading Securities and Available-for-sale Securities [Table] Amortized Cost Trading Securities and Available for Sale Securities, Debt Securities, Amortized Cost Trading Securities and Available for Sale Securities, Debt Securities, Amortized Cost Fair Value Trading Securities and Available for Sale Securities, Debt Securities Trading Securities and Available for Sale Securities, Debt Securities Purchase Price and Fair Value of Assets Acquired Schedule of Business Acquisitions, by Acquisition [Table Text Block] Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed as of Date of Acquisition Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Summary of Intangible Assets Recorded in Connection with Acquisition Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block] Pro Forma Condensed Combined Statement of Earnings Business Acquisition, Pro Forma Information [Table Text Block] Summary of Pro Forma Adjustments to Pro Forma Condensed Statement of Earnings Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table Text Block] Policy benefits for life contracts Liability for Future Policy Benefits, Life Deferred tax assets: Deferred Tax Assets, Net [Abstract] Net operating loss carryforwards Tax credits and other carryforwards Deferred Tax Assets, Tax Credit Carryforwards Insurance reserves Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Reserves Unearned premiums Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Unearned Premiums Reserve Lloyd's underwriting losses taxable in future periods Deferred Tax Assets, Underwriting Losses Deferred Tax Assets, Underwriting Losses Provisions for bad debt Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Allowance for Doubtful Accounts Other deferred tax assets Deferred Tax Assets, Other Gross deferred tax assets Deferred Tax Assets, Gross Valuation allowance Deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Deferred tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Unrealized gains on investments Deferred Tax Liabilities, Investments Intangible assets Deferred Tax Liabilities, Intangible Assets Other deferred tax liabilities Deferred Tax Liabilities, Other Deferred tax liabilities Deferred Tax Liabilities, Gross Net deferred tax liability Deferred Tax Liabilities, Net Gross Unrealized Gains Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Losses Non-OTTI Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax Fair Value Schedule II - Condensed Financial Statements Condensed Financial Information of Parent Company Only Disclosure [Text Block] Schedule of Net Premiums Written and Earned Short-term investments, available-for-sale, at fair value, amortized cost Ordinary shares, par value (in dollars per share) Unaudited Condensed Quarterly Financial Data Quarterly Financial Information [Table Text Block] Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Table] Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Table] Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] Liabilities for unpaid losses and allocated LAE, net of reinsurance Reinsurance recoverable on unpaid losses Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Fair value adjustments Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses Net realized gains (losses) on fixed maturity securities Change in fair value of embedded derivative Kenmare Kenmare [Member] Kenmare [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Acquisition costs Business Combination, Acquisition Related Costs [Member] Business Combination, Acquisition Related Costs [Member] Net premiums earned Premiums Earned, Net [Member] Premiums Earned, Net [Member] First Reserve First Reserve [Member] First Reserve [Member] Corsair Corsair [Member] Corsair [Member] Non-voting preferred stock Non-Voting Preferred Stock [Member] Non-Voting Preferred Stock [Member] Equity Interest Type [Axis] Equity Interest Type [Axis] Equity Interest Issued or Issuable, Type [Domain] Equity Interest Issued or Issuable, Type [Domain] Acquisition consideration Net earnings (losses) of acquiree since acquisition date Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual Earned premiums of acquiree since acquisition date Business Combination, Pro Forma Information, Premiums Earned, Net of Acquiree since Acquisition Date, Actual Business Combination, Pro Forma Information, Premiums Earned, Net of Acquiree since Acquisition Date, Actual Net incurred losses and LAE of acquiree since acquisition date Business Combination, Pro Forma Information, Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims of Acquiree since Acquisition Date, Actual Business Combination, Pro Forma Information, Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims of Acquiree since Acquisition Date, Actual Number of payment installments Business Combination, Consideration Transferred, Number of Payment Installments Business Combination, Consideration Transferred, Number of Payment Installments Cash payments for acquisition Payments to Acquire Businesses, Gross Number of companies acquired Number of Businesses Acquired Percentage of consideration financed through bank loan facility Business Acquisition Percentage Of Consideration Financed Through Borrowings Business Acquisition Percentage Of Consideration Financed Through Borrowings Percentage of consideration paid from cash on hand Business Acquisition Percentage Of Consideration Paid In Cash Business Acquisition Percentage Of Consideration Paid In Cash Fair value adjustment to net unearned premiums acquired Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Unearned Premiums Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Unearned Premiums Amortization of fair value adjustment to net unearned premiums acquired Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Unearned Premiums Amortization Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Unearned Premiums Amortization Unamortized unearned premium fair value adjustment Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Unearned Premiums, Outstanding Balance Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Unearned Premiums, Outstanding Balance Number of wholly-owned insurance vehicles Business Combination, Number of Insurance Vehicles Business Combination, Number of Insurance Vehicles Acquisition consideration including noncontrolling interest consideration Business Combination, Consideration Transferred Including Noncontrolling Interest Consideration Business Combination, Consideration Transferred Including Noncontrolling Interest Consideration Acquisition purchase price (dollars per share) Business Acquisition, Share Price Average closing price of voting ordinary shares prior to trading period (days) Business Acquisition Equity Interest Issued Or Issuable Trading Period Business Acquisition Equity Interest Issued Or Issuable Trading Period Acquisition related transaction expenses Business Acquisition, Transaction Costs Shares issued (in shares) Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Acquisition consideration - noncontrolling interest Business Combination, Consideration Transferred by Noncontrolling Interest Business Combination, Consideration Transferred by Noncontrolling Interest Transaction costs - noncontrolling interest Business Acquisition, Transaction Costs of Noncontrolling Interest Business Acquisition, Transaction Costs of Noncontrolling Interest Conversion of stock, shares issued (in shares) Conversion of Stock, Shares Issued Goodwill recognized Indefinite-lived intangible assets recognized Finite-lived intangible assets recognized Investment in entities Payments to Acquire Investments Number of members appointed to board of directors by parent Noncontrolling Interest, Number of Board Members Appointed by Parent Noncontrolling Interest, Number of Board Members Appointed by Parent Number of members appointed to board of directors by noncontrolling owners Noncontrolling Interest, Number of Board Members Appointed by Noncontrolling Owners Noncontrolling Interest, Number of Board Members Appointed by Noncontrolling Owners Schedule of Future Minimum Rental Payments on Non-Cancellable Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Geographic concentration risk Geographic Concentration Risk [Member] Gross premiums written Premiums Written, Gross [Member] Premiums Written, Gross [Member] Asia Asia [Member] Rest of World Other Geographic Location [Member] Other Geographic Location [Member] Gross premiums written (percent) Schedule V - Valuation and Qualifying Accounts Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Statement of Comprehensive Income [Abstract] NET EARNINGS Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax [Abstract] Unrealized holding gains (losses) on fixed income investments arising during the year Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax Reclassification adjustment for net realized gains included in net earnings Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Unrealized gains (losses) arising during the year, net of reclassification adjustment Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Decrease (increase) in defined benefit pension liability Currency translation adjustment Total other comprehensive gain (loss) Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less comprehensive (income) loss attributable to noncontrolling interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Non-Life Run-Off Non-Life Run-Off and StarStone Segment [Member] Non-Life Run-Off and StarStone Segment [Member] Three non-rated reinsurers Three Non-Rated Reinsurers [Member] Three Non-Rated Reinsurers [Member] Top Ten Reinsurers, Kayla Re Top Ten Reinsurers, Kayla Re [Member] Top Ten Reinsurers, Kayla Re [Member] Top Ten Reinsurers, Lloyd's Syndicates Top Ten Reinsurers, Lloyd's Syndicates [Member] Top Ten Reinsurers, Lloyd's Syndicates [Member] Two Reinsurers Accounting for More than 10% of Total Reinsurance Balances Receivable Two Reinsurer Accounting for More than Ten Percentage of Reinsurance Balances Receivable [Member] Two Reinsurer Accounting for More than Ten Percentage of Reinsurance Balances Receivable [Member] One Reinsurer Accounting for More than 10% of Total Reinsurance Balances Receivable One Reinsurer Accounting For More Than Ten Percentage Of Reinsurance Balances Receivable [Member] One Reinsurer Accounting For More Than Ten Percentage Of Total Reinsurance Balances Receivable. Increase (decrease) in reinsurance recoverable Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Taxation Income Tax Disclosure [Text Block] Reinsurance Balances Recoverable Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document Information [Table] Document Information [Table] Document Information [Line Items] Document Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Trading Symbol Trading Symbol Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Public Float Entity Public Float Noncontrolling Interests Noncontrolling Interest Disclosure [Text Block]