Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Statistical Measurement [Domain] Statistical Measurement [Domain] Investments Investment, Policy [Policy Text Block] SMA1 SMA1 [Member] SMA1 Amortized Cost Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Prior years Prior Year Claims and Claims Adjustment Expense Award Timing Predetermined Award Timing Predetermined [Flag] Related Party Transaction [Axis] Related Party Transaction [Axis] Stock based compensation percent Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-Based Payment Arrangement, Percent Asset Class [Axis] Asset Class [Axis] Entity File Number Entity File Number Cash and Cash Equivalents and Other Assets Cash and Cash Equivalents and Other Assets [Member] Cash and Cash Equivalents and Other Assets Additional paid-in capital: Additional Paid-in Capital [Member] Total unrealized gains for the period recognized in accumulated comprehensive income (loss) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) Fixed maturity securities, available-for sale Fixed Maturity Securities, Available-for-sale [Member] Fixed Maturity Securities, Available-for-sale Fixed maturity securities, measurement input Fixed Maturity Securities, Measurement Input Fixed Maturity Securities, Measurement Input Reclassification adjustment for losses on securities no longer held, net of tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Tabular List, Table Tabular List [Table Text Block] Unearned premiums Unearned Premiums Total Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value Investments Schedule of Investments [Text Block] Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Gross Unrealized Losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Measurement Basis [Axis] Measurement Basis [Axis] Basic earnings per share (in dollar per share) Earnings Per Share, Basic Other expenses Other Expenses Adjustment to Compensation: Adjustment to Compensation [Axis] 12 Months or More Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value Related Party Transactions Related Party Transactions Disclosure [Text Block] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Commission and Fee Income Revenue from Contract with Customer [Text Block] Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Deferred income taxes OCI, Debt Securities, Available-for-Sale, Gain (Loss), before Adjustment, Tax Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Income tax expense Current Income Tax Expense (Benefit) Indirect loans Investment in indirect loans and loan collateral Indirect Loans and Loan Collateral [Member] Indirect Loans and Loan Collateral Gross Unrealized Gains Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain Unsecured subordinated notes Unsecured Subordinated Notes [Member] Unsecured Subordinated Notes Measurement Input Type [Domain] Measurement Input Type [Domain] Adjustment to Compensation, Amount Adjustment to Compensation Amount Affiliated entity Affiliated Entity [Member] Total (losses) gains for the period recognized in net investment gains (losses) attributable to the change in unrealized gains or losses relating to assets held as of period end Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) Total underwriting revenues Underwriting Income (Loss) Commission and fee income Insurance Commissions and Fees Schedule of Ceded Credit Risk Ceded Credit Risk [Table Text Block] Investment expenses Investment Income, Investment Expense, Adjustment Investment Income, Investment Expense, Adjustment Options Share-Based Payment Arrangement, Option [Member] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Accounts and Financing Receivables [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Purchase of equity method investments Payments to Acquire Equity Method Investments Total stockholders’ equity Stockholders' equity beginning balance Stockholders' equity ending balance Equity, Attributable to Parent Agriculture and Credit (Re)insurance Agriculture and Credit (Re)insurance [Member] Agriculture and Credit (Re)insurance Debt Securities, Available-for-Sale [Table] Debt Securities, Available-for-Sale [Table] Comprehensive income Other Comprehensive Income (Loss), Net of Tax [Abstract] Insider Trading Policies and Procedures [Line Items] Schedule of Available-for-Sale, Changes in Allowance for Credit Loss Debt Securities, Available-for-Sale, Allowance for Credit Loss [Table Text Block] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Underwriting, Acquisition and Insurance Expenses Underwriting, Acquisition and Insurance Expenses [Text Block] Underwriting, Acquisition and Insurance Expenses Fixed maturity securities, available-for-sale: Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Total liabilities and stockholders’ equity Liabilities and Equity Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Deferred policy acquisition costs Deferred Policy Acquisition Cost Numerator Preferred Stock Dividends and Other Adjustments [Abstract] Liabilities and stockholders’ equity Liabilities and Equity [Abstract] Market value of trust funds Funds Held under Reinsurance Agreements, Asset Fixed maturity securities OCI, Debt Securities, Available-for-Sale, Gain (Loss), before Adjustment and Tax Premiums receivable, net Premiums Receivable, Net Cover [Abstract] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] High Maximum [Member] Amortized Cost Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss Schedule of Equity Method Investments [Table] Equity Method Investment [Table] Measurement Input, Incremental Cost of Capital Measurement Input, Incremental Cost of Capital [Member] Measurement Input, Incremental Cost of Capital Accounting Policies [Abstract] Total Debt Securities, Available-for-Sale, Unrealized Loss Position Due after ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Available-for-sale and held-to-maturity, fair value Debt Securities, Available-for-Sale And Held-to-Maturity, Unrealized Loss Position [Abstract] Debt Securities, Available-for-Sale And Held-to-Maturity, Unrealized Loss Position Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Debt Instrument [Line Items] Debt Instrument [Line Items] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Pay vs Performance Disclosure [Line Items] Direct premiums Direct Premiums Earned Mortgage Loans Mortgage Receivable [Member] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Effects of Reinsurance [Table] Effects of Reinsurance [Table] Liabilities: Liabilities [Abstract] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income before income taxes Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Schedule of Long-Term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] 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] Difference Equity Method Investment, Difference Between Carrying Amount and Underlying Equity Statement of Stockholders' Equity [Abstract] Operating Segments Operating Segments [Member] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Measurement Input Type [Axis] Measurement Input Type [Axis] Name Measure Name Net income Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Other Managing General Insurance Agent And Broker, Other [Member] Managing General Insurance Agent And Broker, Other Due in less than one year Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Issuances Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances Maturities, calls, transfers and paydowns of fixed maturity securities, available-for-sale Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale Document Fiscal Period Focus Document Fiscal Period Focus Professional Lines Professional Lines [Member] Professional Lines Goodwill and intangible assets, net Intangible Assets, Net (Including Goodwill) Assumed premiums Assumed Premiums Written SUA fee income Managing General Insurance Agent And Broker, Fee Icome [Member] Managing General Insurance Agent And Broker, Fee Icome Award Timing Method Award Timing Method [Text Block] 12 Months or More Debt Securities, Available-for-Sale And Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Debt Securities, Available-for-Sale And Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Award Type [Axis] Award Type [Axis] Total assets Assets Investment, Name [Domain] Investment, Name [Domain] Trading Symbol Trading Symbol Mortgage-backed securities Collateralized Securities [Member] Hospitality Hospitality Portfolio Segment [Member] Hospitality Portfolio Segment Total underwriting expenses Underwriting Expense Underwriting Expense Issuance of shares (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Stock units Stock Units [Member] Stock Units Entity Address, City or Town Entity Address, City or Town Total Debt Securities, Available-for-Sale And Held-to-Maturity, Unrealized Loss Position Debt Securities, Available-for-Sale And Held-to-Maturity, Unrealized Loss Position Cash flows from operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Short-term investments Short Term Investment, Fair Value Disclosure Short Term Investment, Fair Value Disclosure Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Hudson Ventures Fund II LP units Hudson Ventures Fund 2, L.P. [Member] Hudson Ventures Fund 2, L.P. Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Entity Emerging Growth Company Entity Emerging Growth Company Fair Value Total fixed maturity securities, held-to-maturity Debt Securities, Held-to-Maturity, Fair Value Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Less than 12 Months Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Debt Securities, Available-for-Sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Ceded unearned premium Ceded unearned premium Prepaid Reinsurance Premiums Level 2 Fair Value, Inputs, Level 2 [Member] Restricted cash Restricted Cash and Cash Equivalent Equity method investments Carrying Value Recorded investment balance Equity Method Investments Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Deferred ceding commission Deferred Ceding Commission Deferred Ceding Commission Related Party Related Party [Member] Diluted effect of stock notes (in shares) Incremental Common Shares Attributable to Dilutive Effect of Contingently Issuable Shares Equity method investments Equity Method Investments [Member] Common stock, shares outstanding (in shares) Common shares balance at beginning of period (in shares) Common shares balance at ending of period (in shares) Common Stock, Shares, Outstanding Insurance [Abstract] Schedule of Components of Income Tax Expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Gross Unrealized Losses Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss PEO PEO [Member] Transfers into Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Mortgage Loans Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Schedule of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Schedule of Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Common shares Contingently Issuable Instruments, Common Shares [Member] Contingently Issuable Instruments, Common Shares Other Gain on Sale of Other Investments Gain on Sale of Other Investments Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Retained earnings (accumulated deficit): Retained Earnings [Member] Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities Total paid Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Cash and cash equivalents and restricted cash at beginning of period Cash and cash equivalents and restricted cash at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income tax expense Income Tax Expense (Benefit) 12 Months or More Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer Other assets Other Assets Beginning balance Ending balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Investments, fair value disclosure Investments, Fair Value Disclosure Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Mortgage loans not producing income Mortgage Loans not Producing Income, Amount Mortgage Loans not Producing Income, Amount Product and Service [Domain] Product and Service [Domain] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Incurred, net of reinsurance, related to: Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract] Net investment income Net investment income Net Investment Income Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Gross realized gains Gross Realized Investment Gains [Abstract] Gross Realized Investment Gains Construction & Energy Solutions Construction & Energy Solutions [Member] Construction & Energy Solutions Equity securities Equity Securities, FV-NI, Realized Loss Other Income and Expenses [Abstract] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Cash provided by deposit accounting Proceeds From (Payments For) Deposit Accounting Proceeds From (Payments For) Deposit Accounting All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Loans receivable Loans Receivable, Measurement Input Loans Receivable, Measurement Input Loans held-for-investment, term Loans Held-for-Investment, Term Loans Held-for-Investment, Term Total incurred, net of reinsurance Liability For Unpaid Claims And Claims Adjustment Expense, Incurred Claims, Net Liability For Unpaid Claims And Claims Adjustment Expense, Incurred Claims, Net Commitments and Contingencies Disclosure [Abstract] Reinsurance and premium payables Reinsurance Payable Other Unrealized Gain (Loss) on Other Investments Unrealized Gain (Loss) on Other Investments Cash flows from investing activities: Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Change in receivable/payable for securities Payments For (Proceeds From) Sale and Collection of Securities Payments For (Proceeds From) Sale and Collection of Securities Related Party Transactions [Abstract] Fixed maturity securities, available-for sale Proceeds from Sale of Debt Securities, Available-for-Sale Equity Method Investments and Joint Ventures [Abstract] Fixed maturity securities, available-for-sale, at fair value (net of allowance for credit losses of $6,150 and $0, respectively) (amortized cost of $1,638,973 and $1,320,266, respectively) Fair Value Total Total fixed maturity securities, available-for-sale Debt Securities, Available-for-Sale, Excluding Accrued Interest Sales/Disposals Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Reportable Segment Reportable Segment [Member] Reportable Segment Equity Method Investment, Nonconsolidated Investee or Group of Investees Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Equity securities, at fair value Total equity securities Equity Securities, FV-NI Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Current period Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year PEO Total Compensation Amount PEO Total Compensation Amount Net investment gains (losses) Net investment gains (losses) Net investment gains Gain (Loss) on Investments Amortized cost Debt Securities, Available-for-Sale and Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss Equity Components [Axis] Equity Components [Axis] Agency agreement Agency Agreement [Member] Agency Agreement Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Number of reportable segments Number of Reportable Segments Supplemental disclosure of cash flow information: Supplemental Cash Flow Information [Abstract] Other Performance Measure, Amount Other Performance Measure, Amount Arena SOP LP units Arena SOP LP [Member] Arena SOP LP US Treasury and Government US Treasury and Government [Member] Entity Address, State or Province Entity Address, State or Province Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Security, Excluded EPS Calculation [Table] Effects of Reinsurance [Line Items] Effects of Reinsurance [Line Items] Fair Value Fair Value Measurement, Policy [Policy Text Block] Related Party [Domain] Related and Nonrelated Parties [Domain] Mortgage loans Loans Receivable, Fair Value Disclosure Individual: Individual [Axis] Brewer Lane Ventures Fund II LP units Brewer Lane Ventures Fund II, L.P. [Member] Brewer Lane Ventures Fund II, L.P. Weighted-average common shares outstanding Earnings Per Share Reconciliation [Abstract] Subordinated debt, net of debt issuance costs Subordinated Debt, Net [Member] Subordinated Debt, Net Investments: Investments [Abstract] Net cash used in investment activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Total investment income Gross Investment Income (Expense), Operating Gross Investment Income (Expense), Operating Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Net underwriting income Underwriting Income, Net Underwriting Income, Net Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activity Document Fiscal Year Focus Document Fiscal Year Focus Without single maturity date Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Amortized Cost Schedule of Effects of Reinsurance Effects of Reinsurance [Table Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Payments on long term borrowings and trust preferred Repayments of Long-Term Debt Effective tax rate Effective Income Tax Rate Reconciliation, Percent Entity Interactive Data Current Entity Interactive Data Current Equity securities Equity Securities, FV-NI, Realized Gain Equity Method Investment, Nonconsolidated Investee [Axis] Equity Method Investment, Nonconsolidated Investee [Axis] Underwriting, acquisition and insurance expenses Total underwriting, acquisition and insurance expenses Deferred Policy Acquisition Costs, Amortization Expense And Other Cost And Expense, Operating Deferred Policy Acquisition Costs, Amortization Expense And Other Cost And Expense, Operating Carrying Value Reported Value Measurement [Member] Mutual funds: Mutual Fund [Member] Stockholders’ equity Equity [Abstract] Total Realized Investment Gains Realized Investment Gains Current period provision for credit losses Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Credit Loss Expense (Reversal) Investment in direct and indirect loans Proceeds From (Payments To Acquire) Equity Method Investments Proceeds From (Payments To Acquire) Equity Method Investments Earned Premiums Earned, Net [Abstract] Segment Segment Reporting Disclosure [Text Block] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] 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] 12 Months or More Debt Securities, Available-for-Sale And Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer Debt Securities, Available-for-Sale And Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer Reinsurance recoverables, net Reinsurance recoverables Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Available for sale, gross unrealized losses Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Annualized return on equity Return on Equity, Percentage Return on Equity, Percentage Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Weighted average Weighted Average [Member] SMA2 SMA2 [Member] SMA2 RISCOM RISCOM [Member] RISCOM Deferred income taxes Deferred Income Tax Assets, Net Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Less than 12 Months Debt Securities, Available-for-Sale And Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months Debt Securities, Available-for-Sale And Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months Entity Central Index Key Entity Central Index Key PEO Name PEO Name Total revenues Revenues Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Residential mortgage-backed securities Residential Mortgage-Backed Securities [Member] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Losses and loss adjustment expenses Losses and LAE Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Funds held for others Funds Held under Reinsurance Agreements, Liability Direct premiums Direct Premiums Written Arrangement Duration Trading Arrangement Duration Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Debt Securities, Trading, and Equity Securities, FV-NI Debt Securities, Trading, and Equity Securities, FV-NI [Table Text Block] Net premiums Premiums Written, Net Held-to-maturity, fair value Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position [Abstract] Segments [Axis] Segments [Axis] Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Income tax expense at federal statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent SUA commission revenue Managing General Insurance Agent And Broker, Commission Revenue [Member] Managing General Insurance Agent And Broker, Commission Revenue Global Property Global and Property [Member] Global and Property Assets Assets [Abstract] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Debt Instrument [Axis] Debt Instrument [Axis] Total Debt Securities, Available-for-Sale And Held-to-Maturity, Unrealized Loss Position, Accumulated Loss Debt Securities, Available-for-Sale And Held-to-Maturity, Unrealized Loss Position, Accumulated Loss Fair Value Measurements Fair Value Disclosures [Text Block] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Total expenses Benefits, Losses and Expenses Total gross written premiums Premiums Written, Gross Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Commissions Insurance Commissions Accumulated other comprehensive loss: AOCI Attributable to Parent [Member] Investment, Name [Axis] Investment, Name [Axis] Fixed maturity securities, available-for-sale: Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract] Investments [Domain] Investments [Domain] Less: reinsurance recoverable on unpaid claims, beginning of period Plus: reinsurance recoverable on unpaid claims, end of period Ceded unpaid losses and LAE Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Other long-term investments Other Long-Term Investments Fair Value as of Grant Date Award Grant Date Fair Value Entity Registrant Name Entity Registrant Name Percentage of property appraisal value Mortgage Loans on Real Estate, Principal Amount, Percentage of Property Appraisal Value Mortgage Loans on Real Estate, Principal Amount, Percentage of Property Appraisal Value Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Municipal securities Municipal Bonds [Member] Schedule of Subordinated Debt Schedule of Long-Term Debt Instruments [Table Text Block] Adjustments to reconcile net income to net cash provided by operating activities Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity Diluted effect of awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Related Party Transaction [Line Items] Related Party Transaction [Line Items] Document Quarterly Report Document Quarterly Report Less than 12 Months Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Total Assets, Fair Value Disclosure Long-term debt Long-Term Debt, Fair Value Number of securities Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions Schedule of Fair Value Measurement Inputs and Valuation Techniques Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Counterparty Name [Domain] Counterparty Name [Domain] JVM Funds LLC JVM Funds LLC [Member] JVM Funds LLC 12 Months or More Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Purchase of equity securities Payments to Acquire Equity Securities, FV-NI Investment Type [Axis] Investment Type [Axis] Related Party [Axis] Related and Nonrelated Parties [Axis] Corporate Nonsegment Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment [Member] Total investments Investments Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Less than 12 Months Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value Restatement Determination Date: Restatement Determination Date [Axis] Written Premiums Written, Gross [Abstract] Issuance of common stock/Employee equity transactions Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Non-PEO NEO Non-PEO NEO [Member] Change in short-term investments Payments for (Proceeds from) Short-Term Investments Gross Unrealized Gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Name Trading Arrangement, Individual Name Award Type [Domain] Award Type [Domain] Equity Awards Adjustments Equity Awards Adjustments [Member] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Other income (loss) Other income Other Income Compensation Amount Outstanding Recovery Compensation Amount Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Schedule of Liability for Unpaid Claims and Claims Adjustment Expense Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Fair Value Estimate of Fair Value Measurement [Member] Less than 12 Months Debt Securities, Available-for-Sale And Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Debt Securities, Available-for-Sale And Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Preferred stocks: Preferred Stock [Member] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Due after one year through five years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five Name Awards Close in Time to MNPI Disclosures, Individual Name Unrealized gains and losses on investments: Debt Securities, Unrealized Gain (Loss) [Abstract] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] FHLB Loan Term Loan Due August 2029 [Member] Term Loan Due August 2029 Mortgage loans Mortgage Loans, Unrealized Gain (Loss) Mortgage Loans, Unrealized Gain (Loss) Tom Schmitt [Member] Tom Schmitt Revenues: Revenues [Abstract] Due after five years through ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Financial Instruments [Domain] Financial Instruments [Domain] Segments [Domain] Segments [Domain] Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Fixed Maturity Securities, Available-For-Sale Fixed Maturities [Member] Other comprehensive income (loss): Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Retail Retail Portfolio Segment [Member] Retail Portfolio Segment Net Investment Income [Line Items] Net Investment Income [Line Items] Low Minimum [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Company Selected Measure Name Company Selected Measure Name Arena Special Opportunities Fund, LP units Arena Special Opportunities Fund, LP [Member] Arena Special Opportunities Fund, LP U.S. government securities US Government Debt Securities [Member] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Short-term investments and cash Short-term Investments And Cash [Member] Short-term Investments And Cash Purchase of fixed maturity securities, available-for-sale Payments to Acquire Debt Securities, Available-for-Sale Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Subordinated debt, net of debt issuance costs Subordinated Debt Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] All Executive Categories All Executive Categories [Member] Current period Current Year Claims and Claims Adjustment Expense Amortization of policy acquisition costs Deferred Policy Acquisition Costs, Amortization Expense Common stock, $0.01 par value, 500,000,000 shares authorized, 40,486,656 and 40,127,908 shares issued and outstanding, respectively Common Stock, Value, Issued Net earned premiums Net premiums Net earned premium Premiums Earned, Net Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Diluted (in shares) Diluted weighted-average common share equivalents (in shares) Weighted Average Number of Shares Outstanding, Diluted Brewer Lane Ventures Fund II LP Brewer Lane Venture Fund II LP [Member] Brewer Lane Venture Fund II LP Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Fair Value Measured at Net Asset Value Per Share Fair Value Measured at Net Asset Value Per Share [Member] Entity Small Business Entity Small Business Income Tax Disclosure [Abstract] Other operating and general expenses Other Cost and Expense, Operating Revolving credit facility Revolving Line Of Credit Due December 2024 [Member] Revolving Line Of Credit Due December 2024 Document Transition Report Document Transition Report Schedule of Investment Income Investment Income [Table Text Block] Due after one year through five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Ownership % Equity Method Investment, Ownership Percentage Mortgage loans in foreclosure Mortgage Loans in Process of Foreclosure, Amount 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Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Transactional E&S Transactional E&S [Member] Transactional E&S Statement [Table] Statement [Table] Cash flows from financing activities: Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Fixed maturity securities, held-to-maturity: Debt Securities, Available-for-Sale and Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Deposit contracts, assets Deposit Contracts, Assets Total Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Fiscal Year Maturity [Abstract] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities 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for Claims and Claims Adjustment Expense Captives Captives [Member] Captives Termination Date Trading Arrangement Termination Date Net cash used in financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Measure: Measure [Axis] Loss portfolio transfer Reinsurance Recoverable For Loss Portfolio Transfer Reinsurance Recoverable For Loss Portfolio Transfer Basic (in shares) Basic weighted-average common shares (in shares) Weighted Average Number of Shares Outstanding, Basic Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Book value per share (in dollars per share) Book Value, Per Share Book Value, Per Share Schedule Return on Equity and Book Value Per Share Schedule Return on Equity and Book Value Per Share [Table Text Block] Schedule Return on Equity and Book Value Per 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