$MKL
MARKEL GROUP INC. Stock $mkl

$mkl Overview Financials Valuation SEC Filings Company Website

2024 Q4 Form 10-Q Financial Statement

#000109634324000123 Filed on October 30, 2024

Income Statement

Concept	2024 Q4	2024 Q3	2023 Q3
Revenue		$4.611B	$3.375B
YoY Change		36.62%	10.08%
Cost Of Revenue		$1.291B	$1.404B
YoY Change		-8.1%
Gross Profit		$3.321B	$1.971B
YoY Change		68.49%
Gross Profit Margin		72.01%	58.39%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization		$431.7M	$437.9M
YoY Change		-1.43%	1.56%
% of Gross Profit		13.0%	22.22%
Operating Expenses		$3.240B	$3.302B
YoY Change		-1.89%	10.32%
Operating Profit		$1.371B	$72.81M
YoY Change		1783.43%	0.09%
Interest Expense		$53.36M	$44.55M
YoY Change		19.77%	-5.9%
% of Operating Profit		3.89%	61.19%
Other Income/Expense, Net
YoY Change
Pretax Income		$1.206B	$67.50M
YoY Change		1687.11%	-51.96%
Income Tax		$259.4M	$14.24M
% Of Pretax Income		21.5%	21.09%
Net Earnings		$905.0M	$42.59M
YoY Change		2024.77%	-34.85%
Net Earnings / Revenue		19.62%	1.26%
Basic Earnings Per Share		$66.40	$3.15
Diluted Earnings Per Share		$66.25	$3.14
COMMON SHARES
Basic Shares Outstanding	12.86M shares	12.95M shares	13.26M shares
Diluted Shares Outstanding		13.02M shares	13.35M shares

Balance Sheet

Concept	2024 Q3	2023 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$3.873B	$4.355B
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment
YoY Change
Goodwill	$2.740B	$2.623B
YoY Change	4.43%	-6.22%
Intangibles	$1.508B	$1.633B
YoY Change	-7.69%	-3.14%
Long-Term Investments	$849.9M	$582.8M
YoY Change	45.83%	20.64%
Other Assets	$753.5M	$690.0M
YoY Change	9.2%	-45.03%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$62.28B	$52.75B
YoY Change	18.08%	8.94%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities
YoY Change
LONG-TERM LIABILITIES
Long-Term Debt	$4.356B	$3.769B
YoY Change	15.58%	-8.77%
Other Long-Term Liabilities	$5.051B	$4.191B
YoY Change	20.52%	4.16%
Total Long-Term Liabilities	$9.407B	$7.960B
YoY Change	18.18%	-2.39%
TOTAL LIABILITIES
Total Short-Term Liabilities
Total Long-Term Liabilities	$9.407B	$7.960B
Total Liabilities	$44.62B	$38.23B
YoY Change	16.73%	7.53%
SHAREHOLDERS EQUITY
Retained Earnings	$13.06B	$10.78B
YoY Change	21.2%	16.45%
Common Stock	$3.553B	$3.520B
YoY Change	0.95%	1.05%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$17.01B	$14.00B
YoY Change
Total Liabilities & Shareholders Equity	$62.28B	$52.75B
YoY Change	18.08%	8.94%

Cashflow Statement

Concept	2024 Q3	2023 Q3
OPERATING ACTIVITIES
Net Income	$905.0M	$42.59M
YoY Change	2024.77%	-34.85%
Depreciation, Depletion And Amortization	$431.7M	$437.9M
YoY Change	-1.43%	1.56%
Cash From Operating Activities	$890.8M	$955.7M
YoY Change	-6.79%	-0.37%
INVESTING ACTIVITIES
Capital Expenditures	$51.89M	$75.70M
YoY Change	-31.45%	-176.67%
Acquisitions
YoY Change
Other Investing Activities	-$274.2M	-$893.4M
YoY Change	-69.31%	14.36%
Cash From Investing Activities	-$326.1M	-$969.0M
YoY Change	-66.35%	10.12%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-189.5M	-169.4M
YoY Change	11.84%	62.35%
NET CHANGE
Cash From Operating Activities	890.8M	955.7M
Cash From Investing Activities	-326.1M	-969.0M
Cash From Financing Activities	-189.5M	-169.4M
Net Change In Cash	375.2M	-182.7M
YoY Change	-305.39%	630.04%
FREE CASH FLOW
Cash From Operating Activities	$890.8M	$955.7M
Capital Expenditures	$51.89M	$75.70M
Free Cash Flow	$838.9M	$880.0M
YoY Change	-4.67%	-16.83%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Amendment Flag AmendmentFlag	false
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2024
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Entity Central Index Key EntityCentralIndexKey	0001096343
	dei	Entity Address Address Line1 EntityAddressAddressLine1	4521 Highwoods Parkway
	dei	Entity Address City Or Town EntityAddressCityOrTown	Glen Allen
	dei	Security12b Title Security12bTitle	Common Stock, no par value
	dei	Trading Symbol TradingSymbol	MKL
	dei	Security Exchange Name SecurityExchangeName	NYSE
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
	dei	Entity Small Business EntitySmallBusiness	false
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Shell Company EntityShellCompany	false
CY2024Q4	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	12862300	shares
CY2024Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	16265743000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	14932286000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	16067848000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	14372732000	usd
CY2024Q3	us-gaap	Equity Securities Fv Ni Cost EquitySecuritiesFvNiCost	3798549000	usd
CY2023Q4	us-gaap	Equity Securities Fv Ni Cost EquitySecuritiesFvNiCost	3497071000	usd
CY2024Q3	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	11591298000	usd
CY2023Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	9577871000	usd
CY2024Q3	us-gaap	Other Short Term Investments OtherShortTermInvestments	2355738000	usd
CY2023Q4	us-gaap	Other Short Term Investments OtherShortTermInvestments	2571382000	usd
CY2024Q3	us-gaap	Investments Investments	30014884000	usd
CY2023Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	584974000	usd
CY2024Q3	us-gaap	Premiums And Other Receivables Net PremiumsAndOtherReceivablesNet	3909404000	usd
CY2023Q4	us-gaap	Premiums And Other Receivables Net PremiumsAndOtherReceivablesNet	3455306000	usd
CY2024Q3	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	10746213000	usd
CY2023Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	931344000	usd
CY2024Q3	us-gaap	Prepaid Reinsurance Premiums PrepaidReinsurancePremiums	3413314000	usd
CY2023Q4	us-gaap	Prepaid Reinsurance Premiums PrepaidReinsurancePremiums	2365243000	usd
CY2024Q3	us-gaap	Goodwill Goodwill	2739770000	usd
CY2023Q4	us-gaap	Goodwill Goodwill	2624749000	usd
CY2024Q3	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	1507581000	usd
CY2023Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	1588684000	usd
CY2023Q4	us-gaap	Unearned Premiums UnearnedPremiums	6642426000	usd
CY2024Q3	us-gaap	Reinsurance Payable ReinsurancePayable	1448951000	usd
CY2023Q4	us-gaap	Reinsurance Payable ReinsurancePayable	1037722000	usd
CY2024Q3	us-gaap	Debt Instrument Fair Value DebtInstrumentFairValue	4028000000	usd
CY2023Q4	us-gaap	Debt Instrument Fair Value DebtInstrumentFairValue	3353000000	usd
CY2023Q4	us-gaap	Long Term Debt LongTermDebt	3779796000	usd
CY2023Q4	us-gaap	Redeemable Noncontrolling Interest Equity Common Carrying Amount RedeemableNoncontrollingInterestEquityCommonCarryingAmount	469685000	usd
CY2024Q3	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		usd
CY2023Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		usd
CY2024Q3	us-gaap	Preferred Stock Value PreferredStockValue	591891000	usd
CY2023Q4	us-gaap	Preferred Stock Value PreferredStockValue	591891000	usd
CY2024Q3	us-gaap	Common Stock Value CommonStockValue	3552800000	usd
CY2023Q4	us-gaap	Common Stock Value CommonStockValue	3517146000	usd
CY2024Q3	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	13063403000	usd
CY2023Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	11353101000	usd
CY2024Q3	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-193855000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-478210000	usd
CY2024Q3	us-gaap	Stockholders Equity StockholdersEquity	17014239000	usd
CY2023Q4	us-gaap	Stockholders Equity StockholdersEquity	14983928000	usd
CY2024Q3	us-gaap	Minority Interest MinorityInterest	133096000	usd
CY2023Q4	us-gaap	Minority Interest MinorityInterest	72280000	usd
CY2024Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	17147335000	usd
CY2023Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	15056208000	usd
CY2024Q3	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	62283238000	usd
CY2023Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	55045710000	usd
CY2024Q3	us-gaap	Premiums Earned Net PremiumsEarnedNet	2110108000	usd
CY2023Q3	us-gaap	Premiums Earned Net PremiumsEarnedNet	2121745000	usd
	us-gaap	Premiums Earned Net PremiumsEarnedNet	6314834000	usd
	us-gaap	Premiums Earned Net PremiumsEarnedNet	6120592000	usd
CY2024Q3	us-gaap	Net Investment Income NetInvestmentIncome	235477000	usd
CY2023Q3	us-gaap	Net Investment Income NetInvestmentIncome	192207000	usd
	us-gaap	Net Investment Income NetInvestmentIncome	676807000	usd
	us-gaap	Net Investment Income NetInvestmentIncome	521235000	usd
CY2024Q3	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	917530000	usd
CY2023Q3	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	-265917000	usd
	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1689794000	usd
	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	591173000	usd
CY2024Q3	mkl	Products Revenues ProductsRevenues	612277000	usd
CY2023Q3	mkl	Products Revenues ProductsRevenues	601524000	usd
	mkl	Products Revenues ProductsRevenues	2060336000	usd
	mkl	Products Revenues ProductsRevenues	1964332000	usd
CY2024Q3	mkl	Servicesandotherrevenues Servicesandotherrevenues	735872000	usd
CY2023Q3	mkl	Servicesandotherrevenues Servicesandotherrevenues	725627000	usd
	mkl	Servicesandotherrevenues Servicesandotherrevenues	2037991000	usd
	mkl	Servicesandotherrevenues Servicesandotherrevenues	1963779000	usd
CY2024Q3	us-gaap	Revenues Revenues	4611264000	usd
CY2023Q3	us-gaap	Revenues Revenues	3375186000	usd
	us-gaap	Revenues Revenues	12779762000	usd
	us-gaap	Revenues Revenues	11161111000	usd
CY2024Q3	mkl	Underwriting Acquisition And Insurance Expenses UnderwritingAcquisitionAndInsuranceExpenses	743556000	usd
	mkl	Productsexpenses Productsexpenses	1712792000	usd
CY2024Q3	mkl	Servicesandotherexpenses Servicesandotherexpenses	609321000	usd
CY2023Q3	mkl	Servicesandotherexpenses Servicesandotherexpenses	606810000	usd
	mkl	Servicesandotherexpenses Servicesandotherexpenses	1757222000	usd
	us-gaap	Costs And Expenses CostsAndExpenses	9662670000	usd
	us-gaap	Costs And Expenses CostsAndExpenses	9364341000	usd
CY2024Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	1371326000	usd
CY2023Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	72810000	usd
	us-gaap	Operating Income Loss OperatingIncomeLoss	3117092000	usd
	us-gaap	Operating Income Loss OperatingIncomeLoss	1796770000	usd
CY2024Q3	us-gaap	Interest Expense InterestExpense	53361000	usd
CY2023Q3	us-gaap	Interest Expense InterestExpense	44553000	usd
	us-gaap	Interest Expense InterestExpense	151506000	usd
	us-gaap	Interest Expense InterestExpense	141212000	usd
CY2024Q3	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	-111612000	usd
CY2023Q3	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	39246000	usd
	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	-51401000	usd
	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	-8658000	usd
CY2024Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	1206353000	usd
CY2023Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	67503000	usd
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	2914185000	usd
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	1646900000	usd
CY2024Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	259411000	usd
CY2023Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	14235000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	628211000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	339903000	usd
CY2024Q3	us-gaap	Profit Loss ProfitLoss	946942000	usd
CY2023Q3	us-gaap	Profit Loss ProfitLoss	53268000	usd
	us-gaap	Profit Loss ProfitLoss	2285974000	usd
	us-gaap	Profit Loss ProfitLoss	1306997000	usd
CY2024Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	41983000	usd
CY2023Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	10677000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	88130000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	80243000	usd
CY2024Q3	us-gaap	Net Income Loss NetIncomeLoss	904959000	usd
CY2023Q3	us-gaap	Net Income Loss NetIncomeLoss	42591000	usd
	us-gaap	Net Income Loss NetIncomeLoss	2197844000	usd
	us-gaap	Net Income Loss NetIncomeLoss	1226754000	usd
CY2023Q3	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	0	usd
	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	18000000	usd
	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	18000000	usd
CY2024Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	904959000	usd
CY2023Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	42591000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	2179844000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1208754000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-187330000	usd
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	265586000	usd
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-161115000	usd
CY2024Q3	mkl	Reclassification Adjustments For Net Gains Losses Included In Net Income Loss ReclassificationAdjustmentsForNetGainsLossesIncludedInNetIncomeLoss	-254000	usd
CY2024Q3	us-gaap	Oci Liability For Future Policy Benefit Gain Loss After Reclassification Adjustment And Tax OciLiabilityForFuturePolicyBenefitGainLossAfterReclassificationAdjustmentAndTax	-14298000	usd
CY2023Q3	us-gaap	Oci Liability For Future Policy Benefit Gain Loss After Reclassification Adjustment And Tax OciLiabilityForFuturePolicyBenefitGainLossAfterReclassificationAdjustmentAndTax	14609000	usd
	us-gaap	Oci Liability For Future Policy Benefit Gain Loss After Reclassification Adjustment And Tax OciLiabilityForFuturePolicyBenefitGainLossAfterReclassificationAdjustmentAndTax	-1907000	usd
	us-gaap	Oci Liability For Future Policy Benefit Gain Loss After Reclassification Adjustment And Tax OciLiabilityForFuturePolicyBenefitGainLossAfterReclassificationAdjustmentAndTax	8781000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	4236000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	-187000	usd
	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	3306000	usd
	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	2753000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-21000	usd
CY2023Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-96751000	usd
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	2570425000	usd
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	1183740000	usd
CY2024Q3	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	42007000	usd
CY2023Q3	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	10749000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	88226000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	80326000	usd
CY2024Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	1329458000	usd
CY2023Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-107500000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	2482199000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	1103414000	usd
CY2024Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	66.40
CY2023Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.15
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	160.71
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	90.86
CY2024Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	66.25
CY2023Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.14
	dei	Document Period End Date DocumentPeriodEndDate	2024-09-30
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	54-1959284
	dei	City Area Code CityAreaCode	804
	dei	Local Phone Number LocalPhoneNumber	747-0136
CY2023Q4	us-gaap	Investments Investments	26521985000	usd
CY2024Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	3873041000	usd
CY2023Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	9235501000	usd
CY2024Q3	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	967670000	usd
CY2024Q3	us-gaap	Other Assets OtherAssets	4357885000	usd
CY2024Q3	us-gaap	Assets Assets	62283238000	usd
CY2023Q4	us-gaap	Assets Assets	55045710000	usd
CY2024Q3	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	25877478000	usd
CY2023Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	23483321000	usd
CY2024Q3	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	623445000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	649054000	usd
CY2024Q3	us-gaap	Unearned Premiums UnearnedPremiums	7887057000	usd
CY2023Q4	us-gaap	Liabilities Liabilities	39519817000	usd
CY2024Q3	us-gaap	Redeemable Noncontrolling Interest Equity Common Carrying Amount RedeemableNoncontrollingInterestEquityCommonCarryingAmount	515493000	usd
CY2023Q3	mkl	Underwriting Acquisition And Insurance Expenses UnderwritingAcquisitionAndInsuranceExpenses	698129000	usd
	mkl	Underwriting Acquisition And Insurance Expenses UnderwritingAcquisitionAndInsuranceExpenses	2192603000	usd
	mkl	Underwriting Acquisition And Insurance Expenses UnderwritingAcquisitionAndInsuranceExpenses	2071721000	usd
CY2024Q3	mkl	Productsexpenses Productsexpenses	549990000	usd
CY2023Q3	mkl	Productsexpenses Productsexpenses	545567000	usd
	mkl	Productsexpenses Productsexpenses	1766930000	usd
CY2024Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	46459000	usd
CY2023Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	47545000	usd
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	134981000	usd
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	136367000	usd
CY2024Q3	us-gaap	Costs And Expenses CostsAndExpenses	3239938000	usd
CY2023Q3	us-gaap	Costs And Expenses CostsAndExpenses	3302376000	usd
CY2024Q3	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	0	usd
CY2024Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	434310000	usd
CY2023Q3	mkl	Reclassification Adjustments For Net Gains Losses Included In Net Income Loss ReclassificationAdjustmentsForNetGainsLossesIncludedInNetIncomeLoss	-22869000	usd
	mkl	Reclassification Adjustments For Net Gains Losses Included In Net Income Loss ReclassificationAdjustmentsForNetGainsLossesIncludedInNetIncomeLoss	-17406000	usd
	mkl	Reclassification Adjustments For Net Gains Losses Included In Net Income Loss ReclassificationAdjustmentsForNetGainsLossesIncludedInNetIncomeLoss	-26268000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	434564000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-164461000	usd
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	282992000	usd
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-134847000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-20000	usd
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-60000	usd
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-56000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	424523000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-150019000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	284451000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-123257000	usd
CY2024Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	1371465000	usd
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	160.42
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	90.69
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity Registrant Name EntityRegistrantName	MARKEL GROUP INC.
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	VA
	dei	Entity Address State Or Province EntityAddressStateOrProvince	VA
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	23060-6148
CY2023Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	3747060000	usd
CY2024Q3	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	753476000	usd
CY2023Q4	us-gaap	Other Assets OtherAssets	3990864000	usd
CY2024Q3	us-gaap	Long Term Debt LongTermDebt	4356054000	usd
CY2024Q3	us-gaap	Other Liabilities OtherLiabilities	4427425000	usd
CY2023Q4	us-gaap	Other Liabilities OtherLiabilities	3927498000	usd
CY2024Q3	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	1290612000	usd
CY2023Q3	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	1404325000	usd
	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	3810934000	usd
	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	3765215000	usd
	mkl	Servicesandotherexpenses Servicesandotherexpenses	1678246000	usd
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-169800000	usd
CY2024Q3	us-gaap	Liabilities Liabilities	44620410000	usd
	us-gaap	Profit Loss ProfitLoss	2285974000	usd
	us-gaap	Profit Loss ProfitLoss	1306997000	usd
	us-gaap	Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities	-185913000	usd
	us-gaap	Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities	657280000	usd
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	2100061000	usd
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1964277000	usd
	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	1623112000	usd
	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	1359948000	usd
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	2923357000	usd
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	2661587000	usd
	us-gaap	Proceeds From Sale Of Equity Securities Fv Ni ProceedsFromSaleOfEquitySecuritiesFvNi	117006000	usd
	us-gaap	Proceeds From Sale Of Equity Securities Fv Ni ProceedsFromSaleOfEquitySecuritiesFvNi	179665000	usd
	us-gaap	Payments To Acquire Equity Securities Fv Ni PaymentsToAcquireEquitySecuritiesFvNi	434996000	usd
	us-gaap	Payments To Acquire Equity Securities Fv Ni PaymentsToAcquireEquitySecuritiesFvNi	448388000	usd
	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	-305207000	usd
	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	-487839000	usd
	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	204338000	usd
	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	159591000	usd
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	181040000	usd
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	155088000	usd
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	207231000	usd
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	3584000	usd
	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	0	usd
	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	41302000	usd
	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-21276000	usd
	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-16851000	usd
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1884361000	usd
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1342633000	usd
	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	1278485000	usd
	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	475964000	usd
	us-gaap	Repayments Of Debt RepaymentsOfDebt	716543000	usd
	us-gaap	Repayments Of Debt RepaymentsOfDebt	811857000	usd
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	389089000	usd
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	269593000	usd
	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	18000000	usd
	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	18000000	usd
	mkl	Redemption Of Markel Cat Co Re Noncontrolling Interests RedemptionOfMarkelCATCoReNoncontrollingInterests	0	usd
	mkl	Redemption Of Markel Cat Co Re Noncontrolling Interests RedemptionOfMarkelCATCoReNoncontrollingInterests	-88997000	usd
	us-gaap	Payments For Repurchase Of Redeemable Noncontrolling Interest PaymentsForRepurchaseOfRedeemableNoncontrollingInterest	46492000	usd
	us-gaap	Payments For Repurchase Of Redeemable Noncontrolling Interest PaymentsForRepurchaseOfRedeemableNoncontrollingInterest	54371000	usd
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	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	65732000	usd
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-799288000	usd
	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	13051000	usd
	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	993000	usd
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	294483000	usd
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-176651000	usd
CY2023Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4332034000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	5221513000	usd
CY2024Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4626517000	usd
CY2023Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	5044862000	usd
CY2024Q3	us-gaap	Premiums Earned Net PremiumsEarnedNet	2110108000	usd
CY2024Q3	us-gaap	Net Investment Income NetInvestmentIncome	235477000	usd
CY2024Q3	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	917530000	usd
CY2024Q3	mkl	Products Revenues ProductsRevenues	612277000	usd
CY2024Q3	mkl	Servicesandotherrevenues Servicesandotherrevenues	735872000	usd
CY2024Q3	mkl	Operating Revenues OperatingRevenues	4611264000	usd
CY2024Q3	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	1413526000	usd
CY2024Q3	mkl	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 SupplementalInfoForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpenseIncludingAmountsRelatedToLiabilitiesNotIncludedInUnpaidLossesAndLAE	-122914000	usd
CY2024Q3	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	431674000	usd
CY2024Q3	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	311882000	usd
CY2024Q3	mkl	Productsexpenses Productsexpenses	549990000	usd
CY2024Q3	mkl	Servicesandotherexpenses Servicesandotherexpenses	609321000	usd
CY2024Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	46459000	usd
CY2024Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	1371326000	usd
CY2024Q3	us-gaap	Interest Expense InterestExpense	53361000	usd
CY2024Q3	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	-111612000	usd
CY2024Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	1206353000	usd
CY2023Q3	us-gaap	Premiums Earned Net PremiumsEarnedNet	2121745000	usd
CY2023Q3	us-gaap	Net Investment Income NetInvestmentIncome	192207000	usd
CY2023Q3	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	-265917000	usd
CY2023Q3	mkl	Products Revenues ProductsRevenues	601524000	usd
CY2023Q3	mkl	Servicesandotherrevenues Servicesandotherrevenues	725627000	usd
CY2023Q3	mkl	Operating Revenues OperatingRevenues	3375186000	usd
CY2023Q3	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	1434871000	usd
CY2023Q3	mkl	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 SupplementalInfoForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpenseIncludingAmountsRelatedToLiabilitiesNotIncludedInUnpaidLossesAndLAE	-30546000	usd
CY2023Q3	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	437920000	usd
CY2023Q3	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	260209000	usd
CY2023Q3	mkl	Productsexpenses Productsexpenses	545567000	usd
CY2023Q3	mkl	Servicesandotherexpenses Servicesandotherexpenses	606810000	usd
CY2023Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	47545000	usd
CY2023Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	72810000	usd
CY2023Q3	us-gaap	Interest Expense InterestExpense	44553000	usd
CY2023Q3	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	39246000	usd
CY2023Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	67503000	usd
	us-gaap	Premiums Earned Net PremiumsEarnedNet	6314834000	usd
	us-gaap	Net Investment Income NetInvestmentIncome	676807000	usd
	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1689794000	usd
	mkl	Products Revenues ProductsRevenues	2060336000	usd
	mkl	Servicesandotherrevenues Servicesandotherrevenues	2037991000	usd
	mkl	Operating Revenues OperatingRevenues	12779762000	usd
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	4155146000	usd
	mkl	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 SupplementalInfoForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpenseIncludingAmountsRelatedToLiabilitiesNotIncludedInUnpaidLossesAndLAE	-344212000	usd
	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1287900000	usd
	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	904703000	usd
	mkl	Productsexpenses Productsexpenses	1766930000	usd
	mkl	Servicesandotherexpenses Servicesandotherexpenses	1757222000	usd
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	134981000	usd
	us-gaap	Operating Income Loss OperatingIncomeLoss	3117092000	usd
	us-gaap	Interest Expense InterestExpense	151506000	usd
	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	-51401000	usd
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	2914185000	usd
	us-gaap	Premiums Earned Net PremiumsEarnedNet	6120592000	usd
	us-gaap	Net Investment Income NetInvestmentIncome	521235000	usd
	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	591173000	usd
	mkl	Products Revenues ProductsRevenues	1964332000	usd
	mkl	Servicesandotherrevenues Servicesandotherrevenues	1963779000	usd
	mkl	Operating Revenues OperatingRevenues	11161111000	usd
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	3934969000	usd
	mkl	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 SupplementalInfoForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpenseIncludingAmountsRelatedToLiabilitiesNotIncludedInUnpaidLossesAndLAE	-169754000	usd
	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1298771000	usd
	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	772950000	usd
	mkl	Productsexpenses Productsexpenses	1712792000	usd
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	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	136367000	usd
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	us-gaap	Interest Expense InterestExpense	141212000	usd
	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	-8658000	usd
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	1646900000	usd
CY2024Q3	us-gaap	Assets Assets	62283238000	usd
CY2023Q4	us-gaap	Assets Assets	55045710000	usd
CY2024Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	16265743000	usd
CY2024Q3	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	239853000	usd
CY2024Q3	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	437748000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	16067848000	usd
CY2024Q3	mkl	Shortterm Investments Availablefor Sale Amortized Cost Basis ShorttermInvestmentsAvailableforSaleAmortizedCostBasis	2351758000	usd
CY2024Q3	mkl	Shortterm Investments Availablefor Sale Accumulated Gross Unrealized Gain Before Tax ShorttermInvestmentsAvailableforSaleAccumulatedGrossUnrealizedGainBeforeTax	4070000	usd
CY2024Q3	mkl	Shortterm Investments Availablefor Sale Accumulated Gross Unrealized Loss Before Tax ShorttermInvestmentsAvailableforSaleAccumulatedGrossUnrealizedLossBeforeTax	90000	usd
CY2024Q3	mkl	Shortterm Investments Availablefor Sale ShorttermInvestmentsAvailableforSale	2355738000	usd
CY2024Q3	mkl	Investments Availablefor Sale Amortized Cost Basis InvestmentsAvailableforSaleAmortizedCostBasis	18617501000	usd
CY2024Q3	mkl	Investments Availablefor Sale Accumulated Gross Unrealized Gain Before Tax InvestmentsAvailableforSaleAccumulatedGrossUnrealizedGainBeforeTax	243923000	usd
CY2024Q3	mkl	Investments Availablefor Sale Accumulated Gross Unrealized Loss Before Tax InvestmentsAvailableforSaleAccumulatedGrossUnrealizedLossBeforeTax	437838000	usd
CY2024Q3	mkl	Investments Availablefor Sale InvestmentsAvailableforSale	18423586000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	14932286000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	101335000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	660889000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	14372732000	usd
CY2023Q4	mkl	Shortterm Investments Availablefor Sale Amortized Cost Basis ShorttermInvestmentsAvailableforSaleAmortizedCostBasis	2564620000	usd
CY2023Q4	mkl	Shortterm Investments Availablefor Sale Accumulated Gross Unrealized Gain Before Tax ShorttermInvestmentsAvailableforSaleAccumulatedGrossUnrealizedGainBeforeTax	7155000	usd
CY2023Q4	mkl	Shortterm Investments Availablefor Sale Accumulated Gross Unrealized Loss Before Tax ShorttermInvestmentsAvailableforSaleAccumulatedGrossUnrealizedLossBeforeTax	393000	usd
CY2023Q4	mkl	Shortterm Investments Availablefor Sale ShorttermInvestmentsAvailableforSale	2571382000	usd
CY2023Q4	mkl	Investments Availablefor Sale Amortized Cost Basis InvestmentsAvailableforSaleAmortizedCostBasis	17496906000	usd
CY2023Q4	mkl	Investments Availablefor Sale Accumulated Gross Unrealized Gain Before Tax InvestmentsAvailableforSaleAccumulatedGrossUnrealizedGainBeforeTax	108490000	usd
CY2023Q4	mkl	Investments Availablefor Sale Accumulated Gross Unrealized Loss Before Tax InvestmentsAvailableforSaleAccumulatedGrossUnrealizedLossBeforeTax	661282000	usd
CY2023Q4	mkl	Investments Availablefor Sale InvestmentsAvailableforSale	16944114000	usd
CY2024Q3	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position Lessthan12 Months ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPositionLessthan12Months	327973000	usd
CY2024Q3	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position Lessthan12 Months Accumulated Loss ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss	90000	usd
CY2024Q3	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position12 Monthsor Longer ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPosition12MonthsorLonger	0	usd
CY2024Q3	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position12 Monthsor Longer Accumulated Loss ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss	0	usd
CY2024Q3	mkl	Shortterm Investments Availableforsale Unrealized Loss Position Total ShorttermInvestmentsAvailableforsaleUnrealizedLossPositionTotal	327973000	usd
CY2024Q3	mkl	Shortterm Investments Availableforsale Unrealized Loss Position Accumulated Loss ShorttermInvestmentsAvailableforsaleUnrealizedLossPositionAccumulatedLoss	90000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	624978000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	1794000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	7875442000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	436044000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	8500420000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	437838000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	1079	securities
CY2024Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	8500000000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	437800000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	1079	securities
CY2024Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	1032	securities
CY2024Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	7900000000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	436000000.0	usd
CY2023Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position Lessthan12 Months ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPositionLessthan12Months	52601000	usd
CY2023Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position Lessthan12 Months Accumulated Loss ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss	393000	usd
CY2023Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position12 Monthsor Longer ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPosition12MonthsorLonger	0	usd
CY2023Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position12 Monthsor Longer Accumulated Loss ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss	0	usd
CY2023Q4	mkl	Shortterm Investments Availableforsale Unrealized Loss Position Total ShorttermInvestmentsAvailableforsaleUnrealizedLossPositionTotal	52601000	usd
CY2023Q4	mkl	Shortterm Investments Availableforsale Unrealized Loss Position Accumulated Loss ShorttermInvestmentsAvailableforsaleUnrealizedLossPositionAccumulatedLoss	393000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	1467268000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	10821000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	8515061000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	650461000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	9982329000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	661282000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	1386	securities
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	10000000000.0	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	661300000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	1386	securities
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	1131	securities
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	8500000000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	650500000	usd
CY2023Q4	mkl	Investments Available For Sale Allowance For Credit Loss InvestmentsAvailableForSaleAllowanceForCreditLoss	0	usd
CY2024Q3	mkl	Investments Available For Sale Allowance For Credit Loss InvestmentsAvailableForSaleAllowanceForCreditLoss	0	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	1486434000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	1478425000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	5577381000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	5559647000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	4992655000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	4971587000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	1348502000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	1261285000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	13404972000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate	13270944000	usd
CY2024Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	16265743000	usd
CY2024Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	16067848000	usd
CY2024Q3	us-gaap	Investment Income Dividend InvestmentIncomeDividend	36739000	usd
CY2023Q3	us-gaap	Investment Income Dividend InvestmentIncomeDividend	31134000	usd
	us-gaap	Investment Income Dividend InvestmentIncomeDividend	101263000	usd
	us-gaap	Investment Income Dividend InvestmentIncomeDividend	84968000	usd
CY2024Q3	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	240354000	usd
CY2023Q3	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	196266000	usd
	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	691001000	usd
	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	534070000	usd
CY2024Q3	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	4877000	usd
CY2023Q3	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	4059000	usd
	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	14194000	usd
	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	12835000	usd
CY2024Q3	us-gaap	Net Investment Income NetInvestmentIncome	235477000	usd
CY2023Q3	us-gaap	Net Investment Income NetInvestmentIncome	192207000	usd
	us-gaap	Net Investment Income NetInvestmentIncome	676807000	usd
	us-gaap	Net Investment Income NetInvestmentIncome	521235000	usd
CY2024Q3	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	13891000	usd
CY2023Q3	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-36093000	usd
	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-4604000	usd
	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-38159000	usd
CY2024Q3	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	-6652000	usd
CY2023Q3	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	2683000	usd
	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	-11263000	usd
	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	16706000	usd
CY2024Q3	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	910291000	usd
CY2023Q3	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-232507000	usd
	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	1705661000	usd
	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	612626000	usd
CY2024Q3	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	903639000	usd
CY2023Q3	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	-229824000	usd
	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	1694398000	usd
	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	629332000	usd
CY2024Q3	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	917530000	usd
CY2023Q3	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	-265917000	usd
	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1689794000	usd
	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	591173000	usd
CY2024Q3	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	551244000	usd
CY2023Q3	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-208405000	usd
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	358877000	usd
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-170606000	usd
CY2024Q3	us-gaap	Equity Method Investments EquityMethodInvestments	849900000	usd
CY2023Q4	us-gaap	Equity Method Investments EquityMethodInvestments	605900000	usd
CY2024Q3	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	9800000	usd
	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	45400000	usd
CY2023Q3	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	4200000	usd
	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-400000	usd
CY2024Q3	us-gaap	Lease Income LeaseIncome	45726000	usd
CY2023Q3	us-gaap	Lease Income LeaseIncome	50994000	usd
CY2024Q3	mkl	Revenues From Program Services And Other Fronting RevenuesFromProgramServicesAndOtherFronting	47613000	usd
CY2023Q3	mkl	Revenues From Program Services And Other Fronting RevenuesFromProgramServicesAndOtherFronting	39499000	usd
CY2024Q3	mkl	Equity Method And Other Investments Income Loss EquityMethodAndOtherInvestmentsIncomeLoss	8677000	usd
CY2023Q3	mkl	Equity Method And Other Investments Income Loss EquityMethodAndOtherInvestmentsIncomeLoss	-5054000	usd
CY2024Q3	mkl	Other Revenues Losses OtherRevenuesLosses	1501000	usd
CY2023Q3	mkl	Other Revenues Losses OtherRevenuesLosses	13438000	usd
CY2024Q3	mkl	Products Revenues And Services And Other Revenues ProductsRevenuesAndServicesAndOtherRevenues	1348149000	usd
CY2023Q3	mkl	Products Revenues And Services And Other Revenues ProductsRevenuesAndServicesAndOtherRevenues	1327151000	usd
	us-gaap	Lease Income LeaseIncome	123514000	usd
	us-gaap	Lease Income LeaseIncome	130051000	usd
	mkl	Revenues From Program Services And Other Fronting RevenuesFromProgramServicesAndOtherFronting	129861000	usd
	mkl	Revenues From Program Services And Other Fronting RevenuesFromProgramServicesAndOtherFronting	105952000	usd
	mkl	Equity Method And Other Investments Income Loss EquityMethodAndOtherInvestmentsIncomeLoss	45466000	usd
	mkl	Equity Method And Other Investments Income Loss EquityMethodAndOtherInvestmentsIncomeLoss	-12704000	usd
	us-gaap	Other Nonrecurring Gain OtherNonrecurringGain	0	usd
	us-gaap	Other Nonrecurring Gain OtherNonrecurringGain	16923000	usd
	mkl	Other Revenues Losses OtherRevenuesLosses	3987000	usd
	mkl	Other Revenues Losses OtherRevenuesLosses	31127000	usd
	mkl	Products Revenues And Services And Other Revenues ProductsRevenuesAndServicesAndOtherRevenues	4098327000	usd
	mkl	Products Revenues And Services And Other Revenues ProductsRevenuesAndServicesAndOtherRevenues	3928111000	usd
	us-gaap	Schedule Of Liability For Unpaid Claims And Claims Adjustment Expense ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense	<div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The following table presents a reconciliation of consolidated beginning and ending reserves for losses and loss adjustment expenses.</span></div><div><span><br/></span></div><div><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:72.584%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:11.765%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.384%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:11.767%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="9" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Nine Months Ended September 30, </span></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-style:italic;font-weight:400;line-height:100%;text-decoration:underline">(dollars in thousands)</span></td><td colspan="3" style="border-top:1pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">2024</span></td><td colspan="3" style="border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-top:1pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">2023</span></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Gross reserves for losses and loss adjustment expenses, beginning of year</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">23,483,321</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">20,947,898 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Reinsurance recoverables on unpaid losses, beginning of year</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">8,820,567</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">7,994,884 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Net reserves for losses and loss adjustment expenses, beginning of year</span></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">14,662,754</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">12,953,014 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt 2px 19pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Effect of foreign currency rate changes on beginning of year balance</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">45,503</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">16,246 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Adjusted net reserves for losses and loss adjustment expenses, beginning of year</span></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">14,708,257</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">12,969,260 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Incurred losses and loss adjustment expenses:</span></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt 2px 19pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Current accident year</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">4,155,146</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">3,934,969 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt 2px 19pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Prior accident years</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(344,212)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(169,754)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt 2px 19pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Total incurred losses and loss adjustment expenses</span></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">3,810,934</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">3,765,215 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Payments:</span></td><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt 2px 19pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Current accident year</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">444,221</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">419,998 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt 2px 19pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Prior accident years</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">2,415,104</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">2,018,199 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt 2px 19pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Total payments</span></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">2,859,325</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">2,438,197 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Effect of foreign currency rate changes on current year activity</span></td><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">1,861</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">416 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Change in net reserves for losses and loss adjustment expenses of Markel CATCo Re (see note 12)</span></div></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(78,091)</span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(146,895)</span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Reinsurance recoverable for retroactive reinsurance transaction</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">—</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(125,067)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Net reserves for losses and loss adjustment expenses, end of period</span></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">15,583,636</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">14,024,732 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Reinsurance recoverables on unpaid losses</span></td><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">10,293,842</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">8,119,634 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Gross reserves for losses and loss adjustment expenses, end of period</span></td><td style="background-color:#cceeff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#cceeff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">25,877,478</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td style="background-color:#cceeff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">22,144,366 </span></td><td style="background-color:#cceeff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td></tr></table></div>
CY2023Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	23483321000	usd
CY2022Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	20947898000	usd
CY2023Q4	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	8820567000	usd
CY2022Q4	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	7994884000	usd
CY2023Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	14662754000	usd
CY2022Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	12953014000	usd
CY2024Q3	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	45503000	usd
CY2023Q3	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	16246000	usd
CY2023Q4	mkl	Adjusted Liability For Unpaid Claims And Claims Adjustment Expense Net AdjustedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	14708257000	usd
CY2022Q4	mkl	Adjusted Liability For Unpaid Claims And Claims Adjustment Expense Net AdjustedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	12969260000	usd
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	4155146000	usd
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	3934969000	usd
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-344212000	usd
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-169754000	usd
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	3810934000	usd
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	3765215000	usd
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	444221000	usd
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	419998000	usd
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	2415104000	usd
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	2018199000	usd
	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	2859325000	usd
	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	2438197000	usd
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Currency Translation Gain Loss LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCurrencyTranslationGainLoss	1861000	usd
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Currency Translation Gain Loss LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCurrencyTranslationGainLoss	416000	usd
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Business Acquisitions LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitions	-78091000	usd
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Business Acquisitions LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitions	-146895000	usd
	mkl	Reinsurance Recoverable Retroactive Reinsurance Transaction ReinsuranceRecoverableRetroactiveReinsuranceTransaction	0	usd
	mkl	Reinsurance Recoverable Retroactive Reinsurance Transaction ReinsuranceRecoverableRetroactiveReinsuranceTransaction	-125067000	usd
CY2024Q3	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	15583636000	usd
CY2023Q3	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	14024732000	usd
CY2024Q3	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	10293842000	usd
CY2023Q3	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	8119634000	usd
CY2024Q3	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	25877478000	usd
CY2023Q3	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	22144366000	usd
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-344200000	usd
CY2024Q3	us-gaap	Direct Premiums Written DirectPremiumsWritten	3012582000	usd
CY2024Q3	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	459127000	usd
CY2024Q3	us-gaap	Ceded Premiums Written CededPremiumsWritten	1489573000	usd
CY2024Q3	us-gaap	Premiums Written Net PremiumsWrittenNet	1982136000	usd
CY2023Q3	us-gaap	Direct Premiums Written DirectPremiumsWritten	2839412000	usd
CY2023Q3	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	839394000	usd
CY2023Q3	us-gaap	Ceded Premiums Written CededPremiumsWritten	1651001000	usd
CY2023Q3	us-gaap	Premiums Written Net PremiumsWrittenNet	2027805000	usd
CY2024Q3	us-gaap	Direct Premiums Earned DirectPremiumsEarned	2928239000	usd
CY2024Q3	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	935374000	usd
CY2024Q3	us-gaap	Ceded Premiums Earned CededPremiumsEarned	1753505000	usd
CY2024Q3	us-gaap	Premiums Earned Net PremiumsEarnedNet	2110108000	usd
CY2023Q3	us-gaap	Direct Premiums Earned DirectPremiumsEarned	2796788000	usd
CY2023Q3	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	737699000	usd
CY2023Q3	us-gaap	Ceded Premiums Earned CededPremiumsEarned	1412742000	usd
CY2023Q3	us-gaap	Premiums Earned Net PremiumsEarnedNet	2121745000	usd
	us-gaap	Direct Premiums Written DirectPremiumsWritten	9164683000	usd
	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	2959555000	usd
	us-gaap	Ceded Premiums Written CededPremiumsWritten	5631286000	usd
	us-gaap	Premiums Written Net PremiumsWrittenNet	6492952000	usd
	us-gaap	Direct Premiums Written DirectPremiumsWritten	8491896000	usd
	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	2411107000	usd
	us-gaap	Ceded Premiums Written CededPremiumsWritten	4449727000	usd
	us-gaap	Premiums Written Net PremiumsWrittenNet	6453276000	usd
	us-gaap	Direct Premiums Earned DirectPremiumsEarned	8791309000	usd
	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	2106919000	usd
	us-gaap	Ceded Premiums Earned CededPremiumsEarned	4583394000	usd
	us-gaap	Premiums Earned Net PremiumsEarnedNet	6314834000	usd
	us-gaap	Direct Premiums Earned DirectPremiumsEarned	8084663000	usd
	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	1794614000	usd
	us-gaap	Ceded Premiums Earned CededPremiumsEarned	3758685000	usd
	us-gaap	Premiums Earned Net PremiumsEarnedNet	6120592000	usd
CY2024Q3	mkl	Premiums Percentage Ceded To Gross PremiumsPercentageCededToGross	0.45
	mkl	Premiums Percentage Ceded To Gross PremiumsPercentageCededToGross	0.42
CY2023Q3	mkl	Premiums Percentage Ceded To Gross PremiumsPercentageCededToGross	0.40
	mkl	Premiums Percentage Ceded To Gross PremiumsPercentageCededToGross	0.38
CY2024Q3	us-gaap	Premiums Percentage Assumed To Net PremiumsPercentageAssumedToNet	0.44
	us-gaap	Premiums Percentage Assumed To Net PremiumsPercentageAssumedToNet	0.33
CY2023Q3	us-gaap	Premiums Percentage Assumed To Net PremiumsPercentageAssumedToNet	0.35
	us-gaap	Premiums Percentage Assumed To Net PremiumsPercentageAssumedToNet	0.29
CY2024Q3	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Before Reinsurance After Discount Rate Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange	533395000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Before Reinsurance After Discount Rate Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange	557763000	usd
CY2024Q3	mkl	Liability For Future Policy Benefit Deferred Profit Liability LiabilityForFuturePolicyBenefitDeferredProfitLiability	54856000	usd
CY2023Q4	mkl	Liability For Future Policy Benefit Deferred Profit Liability LiabilityForFuturePolicyBenefitDeferredProfitLiability	52287000	usd
CY2024Q3	mkl	Liability For Future Policy Benefit Expected Future Policy Benefit Other LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOther	35194000	usd
CY2023Q4	mkl	Liability For Future Policy Benefit Expected Future Policy Benefit Other LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOther	39004000	usd
CY2024Q3	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	623445000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	649054000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Before Reinsurance After Discount Rate Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange	557763000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Before Reinsurance After Discount Rate Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange	554366000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Original Discount Rate Before Cash Flow And Reinsurance LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance	642877000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Original Discount Rate Before Cash Flow And Reinsurance LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance	667761000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Cumulative Increase Decrease From Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange	0	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Cumulative Increase Decrease From Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange	0	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Cumulative Increase Decrease Of Actual Variance From Expected Experience LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience	-4745000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Cumulative Increase Decrease Of Actual Variance From Expected Experience LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience	-5890000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefit Expected Future Benefit Original Discount Rate Before Reinsurance After Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange	638132000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefit Expected Future Benefit Original Discount Rate Before Reinsurance After Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange	661871000	usd
	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Interest Expense LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense	10596000	usd
	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Interest Expense LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense	11251000	usd
	us-gaap	Liability For Future Policy Benefits Payment For Benefits LiabilityForFuturePolicyBenefitsPaymentForBenefits	37083000	usd
	us-gaap	Liability For Future Policy Benefits Payment For Benefits LiabilityForFuturePolicyBenefitsPaymentForBenefits	39819000	usd
CY2024Q3	mkl	Liability For Future Policy Benefit Expected Future Policy Benefit Effect Of Foreign Currency Rate Changes LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitEffectOfForeignCurrencyRateChanges	4450000	usd
CY2023Q3	mkl	Liability For Future Policy Benefit Expected Future Policy Benefit Effect Of Foreign Currency Rate Changes LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitEffectOfForeignCurrencyRateChanges	-356000	usd
CY2024Q3	us-gaap	Liability For Future Policy Benefit Expected Future Benefit Original Discount Rate Before Reinsurance After Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange	616095000	usd
CY2023Q3	us-gaap	Liability For Future Policy Benefit Expected Future Benefit Original Discount Rate Before Reinsurance After Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange	632947000	usd
CY2024Q3	us-gaap	Aoci Liability For Future Policy Benefit Expected Future Policy Benefit Before Tax AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax	-82700000	usd
CY2023Q3	us-gaap	Aoci Liability For Future Policy Benefit Expected Future Policy Benefit Before Tax AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax	-124511000	usd
CY2024Q3	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Before Reinsurance After Discount Rate Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange	533395000	usd
CY2023Q3	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Before Reinsurance After Discount Rate Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange	508436000	usd
CY2024Q3	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Undiscounted Before Reinsurance LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance	787600000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Undiscounted Before Reinsurance LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance	813600000	usd
CY2024Q3	us-gaap	Liability For Future Policy Benefit Weighted Average Interest Accretion Rate LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate	0.023	rate
CY2023Q4	us-gaap	Liability For Future Policy Benefit Weighted Average Interest Accretion Rate LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate	0.023	rate
CY2024Q3	us-gaap	Liability For Future Policy Benefit Current Weighted Average Discount Rate LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate	0.038	rate
CY2023Q4	us-gaap	Liability For Future Policy Benefit Current Weighted Average Discount Rate LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate	0.038	rate
CY2024Q3	us-gaap	Liability For Future Policy Benefit Weighted Average Duration LiabilityForFuturePolicyBenefitWeightedAverageDuration	P8Y4M24D
CY2023Q4	us-gaap	Liability For Future Policy Benefit Weighted Average Duration LiabilityForFuturePolicyBenefitWeightedAverageDuration	P8Y7M6D
CY2022Q3	mkl	Cash Funding Used To Purchase Markel Cat Co Funds Interests In Markel Cat Co Re CashFundingUsedToPurchaseMarkelCATCoFundsInterestsInMarkelCATCoRe	45100000	usd
CY2022Q2	mkl	Returned Capital From Markel Cat Co Re ReturnedCapitalFromMarkelCATCoRe	24900000	usd
CY2024Q3	mkl	Investment In Markel Cat Co Re InvestmentInMarkelCATCoRe	20100000	usd
CY2023Q4	mkl	Investment In Markel Cat Co Re InvestmentInMarkelCATCoRe	20100000	usd
CY2024Q3	mkl	Percentage Of Markel Cat Co Re Net Equity Held By The Company PercentageOfMarkelCATCoReNetEquityHeldByTheCompany	0.13
CY2023Q4	mkl	Percentage Of Markel Cat Co Re Net Equity Held By The Company PercentageOfMarkelCATCoReNetEquityHeldByTheCompany	0.23
CY2024Q3	mkl	Investment In Markel Cat Co Re InvestmentInMarkelCATCoRe	20100000	usd
CY2023Q4	mkl	Investment In Markel Cat Co Re InvestmentInMarkelCATCoRe	20100000	usd
CY2024Q3	mkl	Tail Risk Cover In Cat Co Transaction TailRiskCoverInCATCoTransaction	95000000.0	usd
CY2024Q3	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	50000000	shares
CY2024Q3	us-gaap	Common Stock No Par Value CommonStockNoParValue	0
CY2024Q3	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	10000000	shares
CY2024Q3	us-gaap	Preferred Stock No Par Value PreferredStockNoParValue	0
CY2023Q2	us-gaap	Dividends Preferred Stock DividendsPreferredStock	18000000.0	usd
CY2024Q2	us-gaap	Dividends Preferred Stock DividendsPreferredStock	18000000.0	usd
CY2024Q2	us-gaap	Preferred Stock Dividends Per Share Cash Paid PreferredStockDividendsPerShareCashPaid	30
CY2023Q2	us-gaap	Preferred Stock Dividends Per Share Cash Paid PreferredStockDividendsPerShareCashPaid	30
CY2024Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	904959000	usd
CY2023Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	42591000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	2179844000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1208754000	usd
CY2024Q3	us-gaap	Temporary Equity Accretion To Redemption Value Adjustment TemporaryEquityAccretionToRedemptionValueAdjustment	42565000	usd
CY2023Q3	us-gaap	Temporary Equity Accretion To Redemption Value Adjustment TemporaryEquityAccretionToRedemptionValueAdjustment	628000	usd
	us-gaap	Temporary Equity Accretion To Redemption Value Adjustment TemporaryEquityAccretionToRedemptionValueAdjustment	81267000	usd
	us-gaap	Temporary Equity Accretion To Redemption Value Adjustment TemporaryEquityAccretionToRedemptionValueAdjustment	-7087000	usd
CY2024Q3	mkl	Adjusted Net Income Loss AdjustedNetIncomeLoss	862394000	usd
CY2023Q3	mkl	Adjusted Net Income Loss AdjustedNetIncomeLoss	41963000	usd
	mkl	Adjusted Net Income Loss AdjustedNetIncomeLoss	2098577000	usd
	mkl	Adjusted Net Income Loss AdjustedNetIncomeLoss	1215841000	usd
CY2024Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	12987000	shares
CY2023Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	13315000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	13058000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	13382000	shares
CY2024Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	13017000	shares
CY2023Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	13345000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	13082000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	13406000	shares
CY2024Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	66.40
CY2023Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.15
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	160.71
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	90.86
CY2024Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	66.25
CY2023Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.14
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	160.42
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	90.69
CY2024Q3	ecd	Non Rule10b51 Arr Adopted Flag NonRule10b51ArrAdoptedFlag	false
CY2024Q3	ecd	Rule10b51 Arr Adopted Flag Rule10b51ArrAdoptedFlag	false
CY2024Q3	ecd	Rule10b51 Arr Trmntd Flag Rule10b51ArrTrmntdFlag	false
CY2024Q3	ecd	Non Rule10b51 Arr Trmntd Flag NonRule10b51ArrTrmntdFlag	false

Files In Submission

Name	View Source	Status
0001096343-24-000123-index-headers.html	Edgar Link	pending
0001096343-24-000123-index.html	Edgar Link	pending
0001096343-24-000123.txt	Edgar Link	pending
0001096343-24-000123-xbrl.zip	Edgar Link	pending
Financial_Report.xlsx	Edgar Link	pending
MetaLinks.json	Edgar Link	pending
mkl-20240930.htm	Edgar Link	pending
mkl-20240930.xsd	Edgar Link	pending
mkl09302024ex311.htm	Edgar Link	pending
mkl09302024ex312.htm	Edgar Link	pending
mkl09302024ex321.htm	Edgar Link	pending
R1.htm	Edgar Link	pending
R10.htm	Edgar Link	pending
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R12.htm	Edgar Link	pending
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R2.htm	Edgar Link	pending
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R38.htm	Edgar Link	pending
R39.htm	Edgar Link	pending
R4.htm	Edgar Link	pending
R40.htm	Edgar Link	pending
R41.htm	Edgar Link	pending
mkl-20240930_cal.xml	Edgar Link	unprocessable
mkl-20240930_def.xml	Edgar Link	unprocessable
mkl-20240930_lab.xml	Edgar Link	unprocessable
mkl-20240930_pre.xml	Edgar Link	unprocessable
mkl-20240930_htm.xml	Edgar Link	completed
R42.htm	Edgar Link	pending
R43.htm	Edgar Link	pending
R44.htm	Edgar Link	pending
R45.htm	Edgar Link	pending
R46.htm	Edgar Link	pending
R47.htm	Edgar Link	pending
R48.htm	Edgar Link	pending
R49.htm	Edgar Link	pending
R5.htm	Edgar Link	pending
R50.htm	Edgar Link	pending
R51.htm	Edgar Link	pending
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R66.htm	Edgar Link	pending
R67.htm	Edgar Link	pending
R7.htm	Edgar Link	pending
R8.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
report.css	Edgar Link	pending
Show.js	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable

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$MKL
MARKEL GROUP INC. Stock $mkl

2024 Q4 Form 10-Q Financial Statement

#000109634324000123 Filed on October 30, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$MKL MARKEL GROUP INC. Stock $mkl

2024 Q4 Form 10-Q Financial Statement

#000109634324000123 Filed on October 30, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$MKL
MARKEL GROUP INC. Stock $mkl