Retroactive reinsurance transaction with Hagerty Re, net losses and loss adjustment expenses Retroactive reinsurance transaction with Hagerty Re, net losses and loss adjustment expenses Retroactive reinsurance transaction with Hagerty Re, net losses and loss adjustment expenses Summary Of Significant Accounting Policies Significant Accounting Policies [Text Block] Favorable (adverse) development on prior years' loss reserves Incurred losses and loss adjustment expenses, prior accident years Prior Year Claims and Claims Adjustment Expense Award Timing Predetermined Award Timing Predetermined [Flag] Entity File Number Entity File Number Tabular List, Table Tabular List [Table Text Block] Unearned premiums Unearned Premiums Consumer and Other Consumer and Other [Member] Consumer and Other Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Equity awards expensed Restricted Stock or Unit Expense Operating Activities [Axis] Operating Activities [Axis] California Wildfires (2025) California Wildfires (2025) [Member] California Wildfires (2025) Available-for-sale fixed maturity securities, gross unrealized holding losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Basic Earnings Per Share, Basic Earnings Per Share, Basic Adjustment to Compensation: Adjustment to Compensation [Axis] Related Party Transactions Disclosure [Text Block] Related Party Transactions Disclosure [Text Block] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Catastrophic Event [Axis] Catastrophic Event [Axis] Products, Services and Other Revenues Revenue from Contract with Customer [Text Block] Schedule of Stock by Class [Table] Stock, Class of Stock [Table] Total Other Comprehensive Income (Loss) Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Segment assets [Member] Continuing Operations [Member] Available-For-Sale Investments Schedule of Available-for-Sale Securities Reconciliation [Table Text Block] Adjustment to Compensation, Amount Adjustment to Compensation Amount Employee Stock Option Share-Based Payment Arrangement, Option [Member] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Cash and Cash Equivalents Cash and Cash Equivalents [Member] Total Shareholders' Equity Equity, Attributable to Parent Fair Value by Measurement Frequency [Axis] Measurement Frequency [Axis] Schedule of Debt Securities, Available-for-sale Securities [Table] Debt Securities, Available-for-Sale [Table] Insider Trading Policies and Procedures [Line Items] Common stock, shares authorized Common Stock, Shares Authorized Services and other revenues Services and other revenues Services and other revenues Issuance of common shares Stock Issued During Period, Shares, New Issues Loss Contingency [Abstract] Loss Contingency [Abstract] Total Liabilities and Equity Liabilities and Equity Fair value, recurring [Member] Fair Value, Recurring [Member] Deferred policy acquisition costs Deferred Policy Acquisition Cost Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Liabilities and Equity [Abstract] Liabilities and Equity [Abstract] Cover [Abstract] Cover [Abstract] Markel Insurance Markel Insurance [Member] Markel Insurance Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Accounting Policies [Abstract] Accounting Policies [Abstract] Available-for-sale securities, estimated fair value Available-for-sale securities, estimated fair value Debt Securities, Available-for-Sale, Unrealized Loss Position Due after ten years, amortized cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Pay vs Performance Disclosure [Line Items] Direct premiums earned Direct Premiums Earned 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] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income (Loss) Before Income Taxes Income (Loss) before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Additions to senior long-term debt and other debt Proceeds from Issuance of Debt Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Purchase of noncontrolling interests Payments for Repurchase of Redeemable Noncontrolling Interest Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Investments, available-for-sale, allowance for credit losses Investments, Available-for-sale, Allowance for Credit Loss Investments, Available-for-sale, Allowance for Credit Loss Comprehensive Income (Loss) to Shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Name Measure Name Due in one year or less, estimated fair value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Non-agency mortgage-backed securities Non-agency mortgage-backed securities [Member] Non-agency mortgage-backed securities Class of Stock [Line Items] Class of Stock [Line Items] Document Fiscal Period Focus Document Fiscal Period Focus Assumed premiums written Assumed Premiums Written Equity method and other investments income (loss) Equity method and other investments income (loss) Equity method and other investments income (loss) Award Timing Method Award Timing Method [Text Block] Unrealized Gain (Loss) on Investments Unrealized Gain (Loss) on Investments [Table Text Block] Award Type [Axis] Award Type [Axis] Senior long-term debt and other debt (estimated fair value of $3,836,000 in 2026 and $3,856,000 in 2025) Long-Term Debt Total Assets Assets Assets Trading Symbol Trading Symbol Gross losses and loss adjustment expenses Gross losses and loss adjustment expenses Policyholder Benefits and Claims Incurred, Direct Professional liability, general liability, marine and energy, and workers' compensation insurance product lines [Member] Professional liability, general liability, marine and energy, and workers' compensation insurance product lines [Member] Professional liability, general liability, marine and energy, and workers' compensation insurance product lines Underwriting [Member] Underwriting Operations [Member] Results attributable to our underwriting operations. Industrial Industrial [Member] Industrial Entity Address, City or Town Entity Address, City or Town OPERATING ACTIVITIES Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Receivable Type [Axis] Receivable Type [Axis] Effect of foreign currency rate changes on cash, cash equivalents, restricted cash, and restricted cash equivalents Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Restricted Stock Units (RSUs) [Member] Restricted Stock Units (RSUs) [Member] Investments, available-for-sale, gross unrealized holding gains Investments, Available-for-Sale, Accumulated Gross Unrealized Gain Before Tax Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Products expenses Products expenses Products expenses Products expenses Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Entity Emerging Growth Company Entity Emerging Growth Company Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Adjusted operating income (loss) Adjusted operating income (loss) Adjusted operating income (loss) 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] Prepaid reinsurance premiums Prepaid Reinsurance Premiums Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Restricted cash and cash equivalents Restricted Cash and Cash Equivalent Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Business Acquisition [Domain] Business Combination [Domain] Short-term investments, estimated fair value Short-term Investments, Available-for-sale, Unrealized Loss Position, Total Amount of short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss. Common Stock, Shares, Outstanding, Beginning Balance Common Stock, Shares, Outstanding, Ending Balance Common Stock, Shares, Outstanding PEO PEO [Member] Schedule Of Revenues From Contracts With Customers By Type Disaggregation of Revenue [Table Text Block] Schedule of Common Stock Outstanding Roll Forward Schedule of Common Stock Outstanding Roll Forward [Table Text Block] Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturity Securities By Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Interest income Investment Income, Interest Capital expenditure Capital expenditure Capital expenditure Capital expenditures attributable to the Industrial & Consumer and Other segments Capital expenditures attributable to the Industrial & Consumer and Other segments [Table Text Block] Capital expenditures attributable to the Industrial & Consumer and Other segments 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] Effect of foreign currency rate changes on current year activity Liability for Unpaid Claims and Claims Adjustment Expense, Foreign Currency Translation Gain (Loss) Retained Earnings [Member] Retained Earnings [Member] Total payments Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Retroactive reinsurance transaction with Hagerty Re Retroactive reinsurance transaction with Hagerty Re [Member] Retroactive reinsurance transaction with Hagerty Re Insurance, banks and other financial institutions [Member] Banks, Trust and Insurance, Equities [Member] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Cash, cash equivalents, restricted cash, and restricted cash equivalents at beginning of period CASH, CASH EQUIVALENTS, RESTRICTED CASH, AND RESTRICTED CASH EQUIVALENTS AT END OF PERIOD Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income Statement [Abstract] Income tax (expense) benefit Income Tax Expense (Benefit) Available-for-sale securities, estimated fair value, 12 months or longer Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer Segment Reporting Information [Line Items] Revenue, Major Customer [Line Items] Attritional Current Year Claims and Claims Adjustment Expense Attritional Current Year Claims and Claims Adjustment Expense Attritional Current Year Claims and Claims Adjustment Expense Other assets Other Assets Fair value, nonrecurring [Member] Fair Value, Nonrecurring [Member] Preferred stock, shares issued Preferred Stock, Shares Issued Intangible assets Intangible Assets, Net (Excluding Goodwill) Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Product and Service [Domain] Product and Service [Domain] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract] Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract] Net investment income Net investment income Net Investment Income Total Shareholders' Equity [Member] Parent [Member] Net Income (Loss) Net Income Net income (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Liabilities measured at fair value on a nonrecurring basis Liabilities, Fair Value Disclosure Percentage of assumed earned premiums to net earned premiums SEC Schedule, 12-17, Insurance Companies, Reinsurance, Premium, Percentage Assumed to Net Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] City Area Code City Area Code Acquisitions, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] 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] Total Equity [Member] Total Equity [Member] Components of equity are the parts of the Total Equity balance. Payables to insurance and reinsurance companies Reinsurance Payable 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 Related Party Transactions [Abstract] Related Party Transactions [Abstract] Other liabilities Other Liabilities Goodwill Goodwill Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Payments, current accident year Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year PEO Total Compensation Amount PEO Total Compensation Amount Effect Of Reinsurance And Retrocessional Reinsurance On Losses and Loss Adjustment Expenses Effects of Reinsurance on Losses and Loss Adjustment Expenses [Table Text Block] Effects of Reinsurance on Losses [Table Text Block] Equity Components [Axis] Equity Components [Axis] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Estimated fair value, sub-total Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Fair Value Short-term investments, available-for-sale, gross unrealized holding losses Short-term Investments, Available-for-Sale, Accumulated Gross Unrealized Loss Before Tax Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on a short-term investment security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Products [Member] Product [Member] Number of Reportable Segments Number of Reportable Segments Middle East conflict (2026) Middle East conflict (2026) [Member] Middle East conflict (2026) Contracts with customers [Member] Contracts with customers [Member] Contracts with customers for promised goods or services. Products revenues Products Revenues Products Revenues Fixed maturity securities, available-for-sale, amortized cost Total fixed maturity securities, amortized cost Debt Securities, Available-for-Sale, Amortized Cost Losses and loss adjustment expenses Net losses and loss adjustment expenses Policyholder Benefits and Claims Incurred, Net Other Performance Measure, Amount Other Performance Measure, Amount Entity Address, State or Province Entity Address, State or Province Effects of Reinsurance [Line Items] Effects of Reinsurance [Line Items] Related Party [Domain] Related and Nonrelated Parties [Domain] Fronting fees Revenues from Program Services and Other Fronting Revenues from Program Services and Other Fronting Percentage of ceded earned premiums to gross earned premiums Premiums Percentage Ceded To Gross Percentage of ceded premiums earned by the entity to gross premiums earned. Total change in fair value of equity securities Equity Securities, FV-NI, Gain (Loss) Individual: Individual [Axis] Net Cash Provided (Used) By Investing Activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation 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] Document Fiscal Year Focus Document Fiscal Year Focus Fixed maturity securities, amortized cost Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Amortized Cost Effect Of Reinsurance And Retrocessional Reinsurance On Premiums Written And Earned 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] Schedule of Gain (Loss) on Securities [Table] Schedule of Gain (Loss) on Securities [Table] Entity Interactive Data Current Entity Interactive Data Current Short-term investments, estimated fair value, 12 months or longer Short-term Investments, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer Amount of short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Catastrophic Event [Domain] Catastrophic Event [Domain] Equity [Abstract] Markel Insurance excluding Global Reinsurance division Markel Insurance excluding Global Reinsurance division [Member] Markel Insurance excluding Global Reinsurance division Short-term investments, available-for-sale, gross unrealized holding gains Short-term Investments, Available-for-Sale, Accumulated Gross Unrealized Gain Before Tax Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on a short-term investment security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Segment Reporting Disclosures Segment Reporting Disclosure [Text Block] Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] 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] U.S. Treasury securities [Member] US Treasury Securities [Member] Reinsurance recoverables Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments Operating revenues Operating revenues Revenue that a company generates from its primary business activities. Short-term investments, gross unrealized holding losses, 12 months or longer Short-term Investments, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Amount of accumulated unrealized loss on investment in short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Other Revenue [Table] Other Revenue [Table] Other Revenue [Table] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Amortization of acquired intangible assets Amortization of acquired intangible assets Amortization of Intangible Assets Entity Central Index Key Entity Central Index Key PEO Name PEO Name Total Operating 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] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Total incurred losses and loss adjustment expenses Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Direct premiums written Direct Premiums Written Short-term investments, gross unrealized holding losses, less than 12 months Short-term Investments, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Amount of accumulated unrealized loss on short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Arrangement Duration Trading Arrangement Duration Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Net premiums written Premiums Written, Net Mortgage-backed securities Mortgage-Backed Securities, Other [Member] Segments [Axis] Segments [Axis] Other, net of taxes Other Comprehensive Income, Other, Net of Tax Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Class of Stock [Domain] Class of Stock [Domain] Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Common stock, no par value Common Stock, No Par Value Other Payment for (Proceeds from) Other Investing Activity Repurchase of common shares Stock Repurchased and Retired During Period, Shares Assets [Abstract] Assets [Abstract] Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss): OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, before Tax Services [Member] Services [Member] Services [Member] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Corporate and eliminations Corporate and eliminations [Member] Corporate and eliminations Fair Value Measurements Fair Value Disclosures [Text Block] Shareholders' equity: Equity, Attributable to Parent [Abstract] 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] Gross premium volume Premiums Written, Gross Entity Address, Address Line One Entity Address, Address Line One Accumulated Other Comprehensive Loss [Member] AOCI Attributable to Parent [Member] Investment Type Categorization [Domain] Investments [Domain] Fair Value as of Grant Date Award Grant Date Fair Value Accounts Receivable, after Allowance for Credit Loss Accounts Receivable, after Allowance for Credit Loss Equity securities, cost Equity Securities, FV-NI, Cost Entity Registrant Name Entity Registrant Name Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Net reserves for losses and loss adjustment expenses of Markel CATCo Re Liability for Unpaid Claims and Claims Adjustment Expense, Business Combination Adjustments to reconcile net income (loss) to net cash provided by operating activities Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity Dilutive potential common shares from restricted stock units and restricted stock Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Total Operating Expenses Costs and Expenses Related Party Transaction [Line Items] Related Party Transaction [Line Items] Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Table] Liability for Unpaid Claim and Claim Adjustment Expense, Change [Table] Document Quarterly Report Document Quarterly Report Available-for-sale securities, estimated fair value, less than 12 months Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Assets measured at fair value on a nonrecurring basis Assets, Fair Value Disclosure Available-for-sale fixed maturity securities in unrealized loss position, number of positions Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] U.S. government-sponsored enterprises [Member] US Government-sponsored Enterprises Debt Securities [Member] Agency mortgage-backed securities Agency mortgage-backed securities [Member] Agency mortgage-backed securities Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Cost of equity securities purchased Payments to Acquire Equity Securities, FV-NI Investment Type [Axis] Investment Type [Axis] Related Party [Axis] Related and Nonrelated Parties [Axis] Total Investments Total Investments Investments Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Other underwriting expenses Other Underwriting Expense Restatement Determination Date: Restatement Determination Date [Axis] Receivables Premiums and Other Receivables, Net Non-PEO NEO Non-PEO NEO [Member] Fronting Fronting [Member] Results attributable to our program services and ILS fronting operations Other Proceeds from (Payment for) Other Financing Activity Net change in short-term investments Payments for (Proceeds from) Short-Term Investments Available-for-sale fixed maturity securities, gross unrealized holding gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Name Trading Arrangement, Individual Name Award Type [Domain] Award Type [Domain] Reinsurance recoverable on unpaid losses, beginning of year Reinsurance recoverable on unpaid losses Reinsurance Recoverables, Incurred but Not Reported Claims Noncontrolling interests Equity, Attributable to Noncontrolling Interest 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] Compensation Amount Outstanding Recovery Compensation Amount Retroactive reinsurance transaction with Hagerty Re, cash payments Retroactive reinsurance transaction with Hagerty Re, cash payments Retroactive reinsurance transaction with Hagerty Re, cash payments Reconciliation Of Consolidated Reserves For Losses And Loss Adjustment Expenses Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Preferred Stock [Member] Preferred Stock [Member] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Due after one year through five years, amortized cost 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 Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] OPERATING REVENUES Revenues [Abstract] Due after five years through ten years, amortized cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Number of available-for-sale fixed maturity securities positions in a continuous unrealized loss position for one year or longer at period end Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Redeemable noncontrolling interests Balance, redeemable noncontrolling interests Balance, redeemable noncontrolling interests Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount Receivables [Line Items] Other Revenue [Line Items] [Line Items] for Other Revenue [Table] Change in net unrealized losses on available-for-sale investments, net of taxes OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Financial Instruments [Domain] Financial Instruments [Domain] Segments [Domain] Segments [Domain] Fixed Maturity Securities [Member] Total fixed maturity securities [Member] Fixed Maturities [Member] Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Schedule of Investment Income, Reported Amounts, by Category [Line Items] Net Investment Income [Line Items] Nephila Reinsurers [Member] Nephila Reinsurers [Member] Nephila Reinsurers [Member] Company Selected Measure Name Company Selected Measure Name Cost of fixed maturity securities purchased Payments to Acquire Debt Securities, Available-for-Sale Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Obligations of states, municipalities and political subdivisions [Member] US States and Political Subdivisions Debt Securities [Member] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] All Executive Categories All Executive Categories [Member] Incurred losses and loss adjustment expenses, current accident year Current Year Claims and Claims Adjustment Expense Amortization of policy acquisition costs Deferred Policy Acquisition Costs, Amortization Expense Stockholders' Equity Note [Abstract] Investments, available-for-sale, gross unrealized holding losses Investments, Available-for-Sale, Accumulated Gross Unrealized Loss Before Tax Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Common stock Common Stock, Value, Issued Earned premiums Net premiums earned Premiums Earned, Net Operating Activities [Domain] Operating Activities [Domain] Contingencies Commitments and Contingencies Disclosure [Text Block] Weighted average diluted common shares outstanding Weighted Average Number of Shares Outstanding, Diluted Commitments and contingencies Commitments and Contingencies Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Business Combination [Axis] Business Combination [Axis] Comprehensive Income (Loss) Comprehensive Income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Entity Small Business Entity Small Business Noncontrolling Interests [Member] Noncontrolling Interest [Member] Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Document Transition Report Document Transition Report Components Of Net Investment Income Investment Income [Table Text Block] Due after one year through five years, estimated fair value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Financial Financial [Member] Financial Short-term investments [Member] Short-term investments [Member] Short-Term Investments [Member] Investments, available-for-sale, estimated fair value Investments, Available-for-Sale Amount of investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Underlying Securities Award Underlying Securities Amount Ceded losses and loss adjustment expenses Policyholder Benefits and Claims Incurred, Ceded Percentage of reinsurance ceded earned premiums to GEP & assumed earned premiums to NEP Percentage of reinsurance ceded earned premiums to GEP & assumed earned premiums to NEP [Table Text Block] Percentage of reinsurance ceded earned premiums to GEP & assumed earned premiums to NEP Total [Domain] Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Due after ten years, estimated fair value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Adjustment of redeemable noncontrolling interests Temporary Equity, Accretion to Redemption Value Services and other expenses Services and other expenses Services and other expenses Services and other expenses Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Senior long-term debt and other debt, fair value Debt Instrument, Fair Value Disclosure Underwriting, acquisition, and insurance expenses Underwriting, acquisition, and insurance expenses Costs incurred during the period related to selling the Company's products and services including the amortization of deferred policy acquisition costs charged to expense in the period, as well as other costs incurred during the period, such as those relating to general administration and policy maintenance. Total Equity Balance Balance Equity, Including Portion Attributable to Noncontrolling Interest Products Revenues and Services and Other Revenues Products Revenues and Services and Other Revenues Products Revenues and Services and Other Revenues Professional liability, credit and surety, and workers' compensation insurance product lines [Member] Professional liability, credit and surety, and workers' compensation insurance product lines [Member] Professional liability, credit and surety, and workers' compensation insurance product lines Other revenues (losses) Other revenues (losses) Other revenues (losses) Document Type Document Type Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Reconciliation Of Segment Assets To The Company's Consolidated Balance Sheets Reconciliation of Assets from Segment to Consolidated [Table Text Block] Unpaid Losses And Loss Adjustment Expenses Liability for Future Policy Benefits and Unpaid Claims Disclosure [Text Block] Name Outstanding Recovery, Individual Name Product and Service [Axis] Product and Service [Axis] Revenue from contracts with customers [Member] Revenue from Contract with Customer Benchmark [Member] Revenue from Contract with Customer Revenue from Contract with Customer, Excluding Assessed Tax Unconsolidated entities managed by Nephila [Member] Unconsolidated entities managed by Nephila [Member] Unconsolidated entities managed by Nephila All Individuals All Individuals [Member] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Additions to property and equipment Payments to Acquire Property, Plant, and Equipment Assumed premiums earned Assumed Premiums Earned Name Forgone Recovery, Individual Name Schedule of Investment Income, Reported Amounts, by Category [Table] Investment Income [Table] Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Hagerty, Inc. [Member] Hagerty, Inc. [Member] Hagerty, Inc. [Member] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Short-term investments, available-for-sale (estimated fair value approximates cost) Short-term investments, available-for-sale Other Short-Term Investments Net income (loss) to shareholders Net Income (Loss) Available to Common Stockholders, Basic Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Company's Segment Disclosures Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Transaction Type [Axis] Transaction Type [Axis] Short-term investments, estimated fair value, less than 12 months Short-term Investments, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months Amount of short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Preferred stock, no par value Preferred Stock, No Par Value Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Redeemable Noncontrolling Interests [Member] Redeemable Noncontrolling Interests, Temporary Equity [Member] The noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Table] Diluted Earnings Per Share, Diluted Earnings Per Share, Diluted Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Title of 12(b) Security Title of 12(b) Security Due after five years through ten years, estimated fair value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 OTHER COMPREHENSIVE INCOME (LOSS) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Earnings Per Share [Line Items] Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] NET INCOME (LOSS) PER COMMON SHARE Earnings Per Share [Abstract] Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract] Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract] Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Repurchase of common stock Stock Repurchased and Retired During Period, Value Other Stockholders' Equity, Other Adjusted net income (loss) to shareholders Adjusted Net Income (Loss) Net income (loss) after adjustment for temporary equity accretion to redemption value. Gain (Loss) on Securities [Line Items] Gain (Loss) on Securities [Line Items] Proceeds from sales of equity securities Proceeds from Sale of Equity Securities, FV-NI SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items] SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items] Award Timing Disclosures [Line Items] Catastrophe Current Year Claims and Claims Adjustment Expense Catastrophe Current Year Claims and Claims Adjustment Expense Catastrophe Current Year Claims and Claims Adjustment Expense Catastrophe Current Year Claims and Claims Adjustment Expense Summary Of Net Investment Gains (Losses) And The Change In Net Unrealized Gains On Available-For-Sale Investments Gain (Loss) on Securities [Table Text Block] Measurement Frequency [Domain] Measurement Frequency [Domain] Net reserves for losses and loss adjustment expenses, beginning of year Net reserves for losses and loss adjustment expenses, end of period Liability for Unpaid Claims and Claims Adjustment Expense, Net Shareholders' Equity Equity [Text Block] Reinsurance Reinsurance [Text Block] Net Income (Loss) to Shareholders Net Income (Loss) Attributable to Parent Expiration Date Trading Arrangement Expiration Date Change in fair value of securities held at the end of the period Equity Securities, FV-NI, Unrealized Gain (Loss) Foreign governments, agencies and supranationals [Member] Debt Security, Government, Non-US [Member] SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract] SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract] Preferred stock, shares authorized Preferred Stock, Shares Authorized Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Ceded premiums written Premiums ceded Ceded Premiums Written Repurchases of common stock Payments for Repurchase of Common Stock Adoption Date Trading Arrangement Adoption Date Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Series A preferred stock [Member] Series A Preferred Stock [Member] Entity Current Reporting Status Entity Current Reporting Status Short-term investments, available-for-sale, amortized cost Short-term Investments, Available-for-Sale, Amortized Cost Basis Amortized cost of short-term investments measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Operating Income (Loss) Operating Income (Loss) Due in one year or less, amortized cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Retained earnings Retained Earnings (Accumulated Deficit) Losses and loss adjustment expenses, prior accident year Supplemental Info For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense Including Amounts Related To Liabilities Not Included In Unpaid Losses And LAE Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related settlement costs, including amounts related to liabilities not classified as unpaid losses and loss adjustment expenses. Transaction [Domain] Transaction [Domain] Schedule of Available-for-sale Securities, Major Types of Debt and Equity Securities [Axis] Financial Instrument [Axis] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Executive Category: Executive Category [Axis] Available-for-sale securities, gross unrealized holding losses, 12 months or longer Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Repayment of senior long-term debt and other debt Repayments of Debt Class of Stock [Axis] Class of Stock [Axis] Interest expense Interest expense Interest Expense, Operating and Nonoperating Current Fiscal Year End Date Current Fiscal Year End Date Available-for-sale securities, gross unrealized holding losses, less than 12 months Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Dividends on equity securities Investment Income, Dividend Effect of foreign currency rate changes on beginning of year balance Liability for Unpaid Claims and Claims Adjustment Expense, Adjustments Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Payments, prior accident years Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Statement [Table] Statement [Table] Schedule of Earnings Per Common Share [Table] Earnings Per Share, Basic, by Common Class, Including Two-Class Method [Table] FINANCING ACTIVITIES Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Industrial, consumer and all other [Member] Industrial, Miscellaneous, and All Others [Member] Shares, Issued, Beginning Balance Shares, Issued, Ending Balance Shares, Issued Corporate and university bonds [Member] Other Corporate Bonds [Member] Available-for-sale securities, gross unrealized holding losses Available-for-sale securities, gross unrealized holding losses Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss Balances Of Assets Measured At Fair Value On A Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Equity securities (cost of $4,125,927 in 2026 and $4,094,745 in 2025) Equity securities Equity Securities, FV-NI, Current Acquisition of EPI Stock Issued During Period, Value, Acquisitions Adjustment and purchase of redeemable noncontrolling interests Temporary Equity, Accretion to Redemption Value, Adjustment Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount All Adjustments to Compensation All Adjustments to Compensation [Member] Amendment Flag Amendment Flag Unpaid losses and loss adjustment expenses Gross reserves for losses and loss adjustment expenses, beginning of year Gross reserves for losses and loss adjustment expenses, end of period Liability for Claims and Claims Adjustment Expense Corporate Operations Corporate Operations [Member] Corporate Operations Termination Date Trading Arrangement Termination Date Net Cash Used By 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] Net foreign exchange gains (losses) Net foreign exchange gains (losses) Realized Gain (Loss), Foreign Currency Transaction, before Tax Educational Partners International Educational Partners International [Member] Educational Partners International Receivable [Domain] Receivable [Domain] Investments, available-for-sale, amortized cost Investments, Available-for-Sale, Amortized Cost Basis Amortized cost of investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Net investment gains (losses) Net investment gains (losses) Net investment gains (losses) The net gains or losses on investments during the period, also including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity. SEC Schedule, 12-17, Insurance Companies, Reinsurance [Table] SEC Schedule, 12-17, Insurance Companies, Reinsurance [Table] Global Reinsurance Division [Member] Global Reinsurance Division [Member] Global Reinsurance Division [Member] Weighted average basic common shares outstanding Weighted Average Number of Shares Outstanding, Basic Retroactive reinsurance transaction with Hagerty Re, unearned premiums Retroactive reinsurance transaction with Hagerty Re, unearned premiums Retroactive reinsurance transaction with Hagerty Re, unearned premiums Schedule Of Net Income (Loss) Per Common Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Short-term investments, available-for-sale, estimated fair value Short-term Investments, Available-for-Sale Amount of short-term investment security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Fund Management Fund Management [Member] Fund Management Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Investment expenses Investment Income, Investment Expense Entity Tax Identification Number Entity Tax Identification Number Fixed maturity securities, estimated fair value Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Fair Value Short-term investments, gross unrealized holding losses Short-term Investments, Available-for-sale, Unrealized Loss Position, Accumulated Loss Amount of accumulated unrealized loss on investment in short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Net realized investment gains (losses) Debt Securities, Available-for-Sale, Realized Gain (Loss) Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Change in fair value of securities sold during the period Equity Securities, FV-NI, Realized Gain (Loss) Adjusted net reserves for losses and loss adjustment expenses, beginning of year Adjusted Liability For Unpaid Claims And Claims Adjustment Expense Net The liability as of the balance sheet date for amounts representing estimated cost of settling unpaid claims under the terms of the underlying insurance policies, less estimated reinsurance recoveries on such claims, adjusted for foreign currency movements, commutations and other events. The liability includes an estimate for claims which have been incurred but not reported. Claim adjustment expenses represent the costs estimated to be incurred in the settlement of unpaid claims. Trading Arrangement: Trading Arrangement [Axis] Total Shareholder Return Amount Total Shareholder Return Amount Insider Trading Arrangements [Line Items] Security Exchange Name Security Exchange Name Leasing revenues Lease Income Total investment income Investment Income, Interest and Dividend Total Liabilities Liabilities Management Fees [Member] Management Fees [Member] Management Fees [Member] Amortized cost, sub-total Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Amortized Cost Ceded premiums earned Ceded Premiums Earned Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Proceeds from sales, maturities, calls, and prepayments of fixed maturity securities Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale OPERATING EXPENSES Operating Expenses [Abstract] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Reinsurance Disclosures [Abstract] Reinsurance Disclosures [Abstract] Statement [Line Items] Statement [Line Items] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and Cash Equivalent Common Stock [Member] Common Stock [Member] Fixed maturity securities, available-for-sale (amortized cost of $18,207,316 in 2026 and $17,895,918 in 2025) Available-for-sale fixed maturity securities, estimated fair value Total fixed maturity securities, estimated fair value Debt Securities, Available-for-Sale Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] Increase (decrease) in cash, cash equivalents, restricted cash, and restricted cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation