$MKL
MARKEL GROUP INC. Stock $mkl

$mkl Overview Financials Valuation SEC Filings Company Website

2024 Q1 Form 10-K Financial Statement

#000109634324000025 Filed on February 23, 2024

Income Statement

Concept	2024 Q1	2023 Q4	2023
Revenue	$4.467B	$4.643B	$15.80B
YoY Change	22.6%	10.25%	35.36%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$434.6M	$44.25M	$1.764B
YoY Change	2.95%	1.05%	886.51%
% of Gross Profit
Operating Expenses	$3.131B	$3.510B	$12.87B
YoY Change	8.35%	14.16%	10.15%
Operating Profit	$1.336B		$2.929B
YoY Change	77.18%		-3249.75%
Interest Expense	$45.55M	-$125.3M	$185.1M
YoY Change	-7.87%	-18.73%	-431.36%
% of Operating Profit	3.41%		6.32%
Other Income/Expense, Net
YoY Change
Pretax Income	$1.342B	$1.007B	$2.654B
YoY Change	99.8%	11.69%	-1882.94%
Income Tax	$292.6M	$212.7M	$552.6M
% Of Pretax Income	21.8%	21.13%	20.82%
Net Earnings	$1.025B	$750.4M	$1.996B
YoY Change	109.8%	13.02%	-723.73%
Net Earnings / Revenue	22.95%	16.16%	12.63%
Basic Earnings Per Share	$75.56		$147.30
Diluted Earnings Per Share	$75.43	$56.45	$147.00
COMMON SHARES
Basic Shares Outstanding	13.11M shares	13.22M shares	13.35M shares
Diluted Shares Outstanding	13.16M shares		13.38M shares

Balance Sheet

Concept	2024 Q1	2023 Q4	2023
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$3.627B	$3.747B	$3.747B
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory		$617.2M
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment		$1.300B	$1.929B
YoY Change		8.33%	11.71%
Goodwill	$2.626B	$2.625B
YoY Change	-0.63%	-0.53%
Intangibles	$1.546B	$1.589B
YoY Change	-9.41%	-9.09%
Long-Term Investments	$633.6M	$605.9M	$26.52B
YoY Change	28.83%	22.65%	19.48%
Other Assets	$649.6M	$585.0M	$608.5M
YoY Change	-33.23%	-46.04%	-45.73%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$57.29B	$55.05B	$55.05B
YoY Change	12.45%	10.55%	10.55%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses			$657.2M
YoY Change			18.55%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due			$76.15M
YoY Change			-80.94%
Total Short-Term Liabilities			$733.4M
YoY Change			-23.13%
LONG-TERM LIABILITIES
Long-Term Debt	$3.855B	$3.780B	$3.704B
YoY Change	-1.06%	-7.89%	-0.01%
Other Long-Term Liabilities	$4.576B	$4.577B	$2.719B
YoY Change	11.98%	9.02%	-1.81%
Total Long-Term Liabilities	$8.432B	$8.356B	$6.423B
YoY Change	5.62%	0.66%	-0.78%
TOTAL LIABILITIES
Total Short-Term Liabilities			$733.4M
Total Long-Term Liabilities	$8.432B	$8.356B	$6.423B
Total Liabilities	$40.97B	$39.52B	$40.06B
YoY Change	11.75%	9.35%	9.08%
SHAREHOLDERS EQUITY
Retained Earnings	$12.18B	$11.35B
YoY Change	18.81%	15.41%
Common Stock	$3.548B	$3.517B
YoY Change	1.17%	0.67%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$15.73B	$14.98B	$14.98B
YoY Change
Total Liabilities & Shareholders Equity	$57.29B	$55.05B	$55.05B
YoY Change	12.45%	10.55%	10.55%

Cashflow Statement

Concept	2024 Q1	2023 Q4	2023
OPERATING ACTIVITIES
Net Income	$1.025B	$750.4M	$1.996B
YoY Change	109.8%	13.02%	-723.73%
Depreciation, Depletion And Amortization	$434.6M	$44.25M	$1.764B
YoY Change	2.95%	1.05%	886.51%
Cash From Operating Activities	$630.7M	$822.5M	$2.787B
YoY Change	121.92%	-0.8%	2.86%
INVESTING ACTIVITIES
Capital Expenditures	$71.95M	$103.5M	$258.6M
YoY Change	93.53%	127.86%	1.53%
Acquisitions	$48.98M		$3.584M
YoY Change			-95.46%
Other Investing Activities	$2.419M	-$1.257B	-$23.08M
YoY Change	42.63%	268.28%	-378.29%
Cash From Investing Activities	-$564.2M	-$1.361B	-$2.704B
YoY Change	419.82%	251.79%	61.87%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net			$445.5M
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-$102.7M	-200.4M	-$999.7M
YoY Change	-75.07%	92.23%	67.93%
NET CHANGE
Cash From Operating Activities	$630.7M	822.5M	$2.787B
Cash From Investing Activities	-$564.2M	-1.361B	-$2.704B
Cash From Financing Activities	-$102.7M	-200.4M	-$999.7M
Net Change In Cash	-$55.29M	-738.9M	-$889.5M
YoY Change	-74.48%	-318.59%	-361.18%
FREE CASH FLOW
Cash From Operating Activities	$630.7M	$822.5M	$2.787B
Capital Expenditures	$71.95M	$103.5M	$258.6M
Free Cash Flow	$558.7M	$719.0M	$2.528B
YoY Change	126.19%	-8.26%	2.99%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2023	dei	Document Annual Report DocumentAnnualReport	true
CY2023	dei	Document Transition Report DocumentTransitionReport	false
CY2023	dei	Amendment Flag AmendmentFlag	false
CY2023	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2023
CY2023	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2023	dei	Entity Central Index Key EntityCentralIndexKey	0001096343
CY2023	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
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CY2022	us-gaap	Fair Value Recurring Basis Unobservable Input Reconciliation Asset Gain Loss Statement Of Income Extensible List FairValueRecurringBasisUnobservableInputReconciliationAssetGainLossStatementOfIncomeExtensibleList	http://www.markelcorp.com/20231231#NetInvestmentGainsLosses
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CY2022Q4	us-gaap	Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OtherAssets
CY2023Q4	us-gaap	Operating Lease Liability Statement Of Financial Position Extensible List OperatingLeaseLiabilityStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OtherLiabilities
CY2022Q4	us-gaap	Operating Lease Liability Statement Of Financial Position Extensible List OperatingLeaseLiabilityStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OtherLiabilities
CY2023Q4	us-gaap	Operating Lease Liability Statement Of Financial Position Extensible List OperatingLeaseLiabilityStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OtherLiabilities
CY2023	dei	Entity File Number EntityFileNumber	001-15811
CY2023	dei	Entity Registrant Name EntityRegistrantName	MARKEL GROUP INC.
CY2023	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	VA
CY2023	dei	Security12b Title Security12bTitle	Common Stock, no par value
CY2023	dei	Trading Symbol TradingSymbol	MKL
CY2023	dei	Security Exchange Name SecurityExchangeName	NYSE
CY2023	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2023	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2023	dei	Icfr Auditor Attestation Flag IcfrAuditorAttestationFlag	true
CY2023	dei	Document Fin Stmt Error Correction Flag DocumentFinStmtErrorCorrectionFlag	false
CY2023	dei	Entity Shell Company EntityShellCompany	false
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CY2023Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	14932286000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	14932286000	usd
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CY2022Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	12805887000	usd
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CY2022Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	4137432000	usd
CY2023Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	584974000	usd
CY2022Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	1084081000	usd
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CY2022Q4	us-gaap	Premiums And Other Receivables Net PremiumsAndOtherReceivablesNet	2961056000	usd
CY2023Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	9235501000	usd
CY2022Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	8446745000	usd
CY2023Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	931344000	usd
CY2022Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	925483000	usd
CY2023Q4	us-gaap	Prepaid Reinsurance Premiums PrepaidReinsurancePremiums	2365243000	usd
CY2022Q4	us-gaap	Prepaid Reinsurance Premiums PrepaidReinsurancePremiums	2066114000	usd
CY2023Q4	us-gaap	Goodwill Goodwill	2624749000	usd
CY2022Q4	us-gaap	Goodwill Goodwill	2638838000	usd
CY2023Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	1588684000	usd
CY2022Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	1747464000	usd
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CY2023Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	649054000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	650721000	usd
CY2023Q4	us-gaap	Unearned Premiums UnearnedPremiums	6642426000	usd
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CY2022Q4	us-gaap	Other Liabilities OtherLiabilities	3461482000	usd
CY2023Q4	us-gaap	Liabilities Liabilities	39519817000	usd
CY2022Q4	us-gaap	Liabilities Liabilities	36054220000	usd
CY2023Q4	us-gaap	Redeemable Noncontrolling Interest Equity Common Carrying Amount RedeemableNoncontrollingInterestEquityCommonCarryingAmount	469685000	usd
CY2022Q4	us-gaap	Redeemable Noncontrolling Interest Equity Common Carrying Amount RedeemableNoncontrollingInterestEquityCommonCarryingAmount	523154000	usd
CY2023Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		usd
CY2022Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		usd
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CY2022Q4	us-gaap	Preferred Stock Value PreferredStockValue	591891000	usd
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CY2022Q4	us-gaap	Minority Interest MinorityInterest	62791000	usd
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CY2022Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	49791259000	usd
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CY2022	us-gaap	Net Investment Income NetInvestmentIncome	446755000	usd
CY2021	us-gaap	Net Investment Income NetInvestmentIncome	367417000	usd
CY2023	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1524054000	usd
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CY2021	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1978534000	usd
CY2023	mkl	Products Revenues ProductsRevenues	2545053000	usd
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CY2023	mkl	Servicesandotherrevenues Servicesandotherrevenues	2704512000	usd
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CY2022	us-gaap	Oci Liability For Future Policy Benefit Gain Loss After Reclassification Adjustment And Tax Parent OciLiabilityForFuturePolicyBenefitGainLossAfterReclassificationAdjustmentAndTaxParent	149874000	usd
CY2021	us-gaap	Oci Liability For Future Policy Benefit Gain Loss After Reclassification Adjustment And Tax Parent OciLiabilityForFuturePolicyBenefitGainLossAfterReclassificationAdjustmentAndTaxParent	49411000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	4704000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	-9259000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	-213000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-74000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-24730000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-8390000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	289338000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-989485000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-347111000	usd
CY2023	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	2390428000	usd
CY2022	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-1092842000	usd
CY2021	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	2098756000	usd
CY2023	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	105084000	usd
CY2022	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	112937000	usd
CY2021	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	22730000	usd
CY2023	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	2285344000	usd
CY2022	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-1205779000	usd
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	2076026000	usd
CY2023	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	147.32
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-23.72
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	176.79
CY2023	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	146.98
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-23.72
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	176.38
CY2023	us-gaap	Profit Loss ProfitLoss	2101090000	usd
CY2022	us-gaap	Profit Loss ProfitLoss	-103357000	usd
CY2021	us-gaap	Profit Loss ProfitLoss	2445867000	usd
CY2023	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	-233798000	usd
CY2022	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	282325000	usd
CY2021	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	-453408000	usd
CY2023	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	259924000	usd
CY2022	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	366954000	usd
CY2021	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	336393000	usd
CY2023	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	1524054000	usd
CY2022	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	-1595733000	usd
CY2021	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	1978534000	usd
CY2023	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	-90045000	usd
CY2022	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	137832000	usd
CY2021	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	71902000	usd
CY2023	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	18965000	usd
CY2022	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	225832000	usd
CY2021	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	22085000	usd
CY2023	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	usd
CY2022	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	80000000	usd
CY2021	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	usd
CY2023	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	486305000	usd
CY2022	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	653261000	usd
CY2021	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	372491000	usd
CY2023	us-gaap	Increase Decrease In Reinsurance Recoverable IncreaseDecreaseInReinsuranceRecoverable	767509000	usd
CY2022	us-gaap	Increase Decrease In Reinsurance Recoverable IncreaseDecreaseInReinsuranceRecoverable	1168483000	usd
CY2021	us-gaap	Increase Decrease In Reinsurance Recoverable IncreaseDecreaseInReinsuranceRecoverable	1312258000	usd
CY2023	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	1602000	usd
CY2022	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	140630000	usd
CY2021	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	139609000	usd
CY2023	us-gaap	Increase Decrease In Prepaid Reinsurance Premiums IncreaseDecreaseInPrepaidReinsurancePremiums	298049000	usd
CY2022	us-gaap	Increase Decrease In Prepaid Reinsurance Premiums IncreaseDecreaseInPrepaidReinsurancePremiums	271292000	usd
CY2021	us-gaap	Increase Decrease In Prepaid Reinsurance Premiums IncreaseDecreaseInPrepaidReinsurancePremiums	347982000	usd
CY2023	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	2443178000	usd
CY2022	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	2383268000	usd
CY2021	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	2042486000	usd
CY2023	us-gaap	Increase Decrease In Life Insurance Liabilities IncreaseDecreaseInLifeInsuranceLiabilities	-48327000	usd
CY2022	us-gaap	Increase Decrease In Life Insurance Liabilities IncreaseDecreaseInLifeInsuranceLiabilities	-44693000	usd
CY2021	us-gaap	Increase Decrease In Life Insurance Liabilities IncreaseDecreaseInLifeInsuranceLiabilities	-52226000	usd
CY2023	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	400017000	usd
CY2022	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	886393000	usd
CY2021	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	970246000	usd
CY2023	us-gaap	Increase Decrease In Reinsurance Payables IncreaseDecreaseInReinsurancePayables	365378000	usd
CY2022	us-gaap	Increase Decrease In Reinsurance Payables IncreaseDecreaseInReinsurancePayables	210810000	usd
CY2021	us-gaap	Increase Decrease In Reinsurance Payables IncreaseDecreaseInReinsurancePayables	131559000	usd
CY2023	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-38188000	usd
CY2022	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-213989000	usd
CY2021	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-191195000	usd
CY2023	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	2786807000	usd
CY2022	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	2709442000	usd
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	2274067000	usd
CY2023	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	2126586000	usd
CY2022	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	1152335000	usd
CY2021	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	708111000	usd
CY2023	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	4302864000	usd
CY2022	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	2112066000	usd
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	3165323000	usd
CY2023	us-gaap	Proceeds From Sale Of Equity Securities Fv Ni ProceedsFromSaleOfEquitySecuritiesFvNi	298582000	usd
CY2022	us-gaap	Proceeds From Sale Of Equity Securities Fv Ni ProceedsFromSaleOfEquitySecuritiesFvNi	242010000	usd
CY2021	us-gaap	Proceeds From Sale Of Equity Securities Fv Ni ProceedsFromSaleOfEquitySecuritiesFvNi	200570000	usd
CY2023	us-gaap	Payments To Acquire Equity Securities Fv Ni PaymentsToAcquireEquitySecuritiesFvNi	638306000	usd
CY2022	us-gaap	Payments To Acquire Equity Securities Fv Ni PaymentsToAcquireEquitySecuritiesFvNi	442991000	usd
CY2021	us-gaap	Payments To Acquire Equity Securities Fv Ni PaymentsToAcquireEquitySecuritiesFvNi	255436000	usd
CY2023	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	-202930000	usd
CY2022	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	846019000	usd
CY2021	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	-228955000	usd
CY2023	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	192715000	usd
CY2022	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	20051000	usd
CY2021	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	48922000	usd
CY2023	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	258619000	usd
CY2022	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	254712000	usd
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	145249000	usd
CY2023	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	3584000	usd
CY2022	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	79000000	usd
CY2021	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	517439000	usd
CY2023	mkl	Consolidation Of Markel Cat Co Re Net ConsolidationOfMarkelCATCoReNet	0	usd
CY2022	mkl	Consolidation Of Markel Cat Co Re Net ConsolidationOfMarkelCATCoReNet	629955000	usd
CY2021	mkl	Consolidation Of Markel Cat Co Re Net ConsolidationOfMarkelCATCoReNet	0	usd
CY2023	mkl	Distributions To Markel Cat Co Re Noncontrolling Interests For Buy Out Transaction DistributionsToMarkelCATCoReNoncontrollingInterestsForBuyOutTransaction	0	usd
CY2022	mkl	Distributions To Markel Cat Co Re Noncontrolling Interests For Buy Out Transaction DistributionsToMarkelCATCoReNoncontrollingInterestsForBuyOutTransaction	169380000	usd
CY2021	mkl	Distributions To Markel Cat Co Re Noncontrolling Interests For Buy Out Transaction DistributionsToMarkelCATCoReNoncontrollingInterestsForBuyOutTransaction	0	usd
CY2023	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	41302000	usd
CY2022	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	201370000	usd
CY2023	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-23081000	usd
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-2937802000	usd
CY2022	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	1034052000	usd
CY2021	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	1198505000	usd
CY2023	us-gaap	Repayments Of Debt RepaymentsOfDebt	949636000	usd
CY2022	us-gaap	Repayments Of Debt RepaymentsOfDebt	1255005000	usd
CY2021	us-gaap	Repayments Of Debt RepaymentsOfDebt	486730000	usd
CY2023	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	445479000	usd
CY2022	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	290796000	usd
CY2021	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	206518000	usd
CY2023	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	36000000	usd
CY2022	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	36000000	usd
CY2021	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	36000000	usd
CY2023	us-gaap	Payments For Repurchase Of Redeemable Noncontrolling Interest PaymentsForRepurchaseOfRedeemableNoncontrollingInterest	63371000	usd
CY2022	us-gaap	Payments For Repurchase Of Redeemable Noncontrolling Interest PaymentsForRepurchaseOfRedeemableNoncontrollingInterest	30000	usd
CY2021	us-gaap	Payments For Repurchase Of Redeemable Noncontrolling Interest PaymentsForRepurchaseOfRedeemableNoncontrollingInterest	57134000	usd
CY2023	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	88997000	usd
CY2022	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	0	usd
CY2021	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	0	usd
CY2023	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-41205000	usd
CY2022	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-47532000	usd
CY2021	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-42356000	usd
CY2023	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-999716000	usd
CY2022	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-595311000	usd
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	369767000	usd
CY2023	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	27037000	usd
CY2022	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-103361000	usd
CY2021	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-41734000	usd
CY2023	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-889479000	usd
CY2022	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	340566000	usd
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-335702000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	5221513000	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4880947000	usd
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	5216649000	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
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4880947000	usd
CY2023	us-gaap	Use Of Estimates UseOfEstimates	Use of Estimates.<span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Management periodically reviews its estimates and assumptions. Quarterly reviews include evaluating the adequacy of reserves for unpaid losses and loss adjustment expenses and contingencies. Estimates and assumptions for goodwill and intangible assets are reviewed in conjunction with an acquisition, and goodwill and indefinite-lived intangible assets are reassessed at least annually for impairment. Actual results may differ materially from the estimates and assumptions used in preparing the consolidated financial statements.</span>
CY2023	mkl	Deferred Policy Acquisition Cost Amortization Period DeferredPolicyAcquisitionCostAmortizationPeriod	P1Y
CY2023Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	1300000000	usd
CY2022Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	1200000000	usd
CY2023Q4	us-gaap	Inventory Net InventoryNet	617200000	usd
CY2022Q4	us-gaap	Inventory Net InventoryNet	639600000	usd
CY2023	mkl	Tax Benefit Greater Than Fifty Percent TaxBenefitGreaterThanFiftyPercent	0.50
CY2023	mkl	Revenue Recognition Period Insurance Premiums RevenueRecognitionPeriodInsurancePremiums	P1Y
CY2023	us-gaap	Premiums Earned Net PremiumsEarnedNet	8295479000	usd
CY2023	us-gaap	Net Investment Income NetInvestmentIncome	734532000	usd
CY2023	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1524054000	usd
CY2023	mkl	Products Revenues ProductsRevenues	2545053000	usd
CY2023	mkl	Servicesandotherrevenues Servicesandotherrevenues	2704512000	usd
CY2023	us-gaap	Revenues Revenues	15803630000	usd
CY2023	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	5360559000	usd
CY2023	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	-38550000	usd
CY2023	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1763670000	usd
CY2023	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	1077064000	usd
CY2023	mkl	Productsexpenses Productsexpenses	2220676000	usd
CY2023	mkl	Servicesandotherexpenses Servicesandotherexpenses	2310769000	usd
CY2023	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	180614000	usd
CY2023	mkl	Segment Profit Loss SegmentProfitLoss	2928828000	usd
CY2023	us-gaap	Interest Expense InterestExpense	185077000	usd
CY2023	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	-90045000	usd
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	2653706000	usd
CY2022	us-gaap	Premiums Earned Net PremiumsEarnedNet	7587792000	usd
CY2022	us-gaap	Net Investment Income NetInvestmentIncome	446755000	usd
CY2022	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	-1595733000	usd
CY2022	mkl	Products Revenues ProductsRevenues	2427096000	usd
CY2022	mkl	Servicesandotherrevenues Servicesandotherrevenues	2809425000	usd
CY2022	us-gaap	Revenues Revenues	11675335000	usd
CY2022	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	4613035000	usd
CY2022	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	-167446000	usd
CY2022	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1655106000	usd
CY2022	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	860477000	usd
CY2022	mkl	Productsexpenses Productsexpenses	2241736000	usd
CY2022	mkl	Servicesandotherexpenses Servicesandotherexpenses	2306985000	usd
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	178778000	usd
CY2022	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	80000000	usd
CY2022	mkl	Segment Profit Loss SegmentProfitLoss	-93336000	usd
CY2022	us-gaap	Interest Expense InterestExpense	196062000	usd
CY2022	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	137832000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-151566000	usd
CY2021	us-gaap	Premiums Earned Net PremiumsEarnedNet	6503029000	usd
CY2021	us-gaap	Net Investment Income NetInvestmentIncome	367417000	usd
CY2021	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1978534000	usd
CY2021	mkl	Products Revenues ProductsRevenues	1712120000	usd
CY2021	mkl	Servicesandotherrevenues Servicesandotherrevenues	2285325000	usd
CY2021	us-gaap	Revenues Revenues	12846425000	usd
CY2021	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	4061000000	usd
CY2021	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	-479795000	usd
CY2021	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1419266000	usd
CY2021	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	874473000	usd
CY2021	mkl	Productsexpenses Productsexpenses	1544506000	usd
CY2021	mkl	Servicesandotherexpenses Servicesandotherexpenses	2024931000	usd
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	160539000	usd
CY2021	mkl	Segment Profit Loss SegmentProfitLoss	3241505000	usd
CY2021	us-gaap	Interest Expense InterestExpense	183579000	usd
CY2021	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	71902000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	3129828000	usd
CY2023	us-gaap	Premiums Earned Net PremiumsEarnedNet	8295479000	usd
CY2022	us-gaap	Premiums Earned Net PremiumsEarnedNet	7587792000	usd
CY2021	us-gaap	Premiums Earned Net PremiumsEarnedNet	6503029000	usd
CY2023Q4	us-gaap	Assets Assets	55045710000	usd
CY2022Q4	us-gaap	Assets Assets	49791259000	usd
CY2023	us-gaap	Premiums Written Gross PremiumsWrittenGross	14002237000	usd
CY2022	us-gaap	Premiums Written Gross PremiumsWrittenGross	13201682000	usd
CY2021	us-gaap	Premiums Written Gross PremiumsWrittenGross	11438682000	usd
CY2023	us-gaap	Premiums Written Net PremiumsWrittenNet	8397575000	usd
CY2022	us-gaap	Premiums Written Net PremiumsWrittenNet	8203390000	usd
CY2021	us-gaap	Premiums Written Net PremiumsWrittenNet	7119731000	usd
CY2023Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	931344000	usd
CY2023Q4	us-gaap	Unearned Premiums UnearnedPremiums	6642426000	usd
CY2023Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	23483321000	usd
CY2022Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	925483000	usd
CY2022Q4	us-gaap	Unearned Premiums UnearnedPremiums	6220748000	usd
CY2022Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	20947898000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	14932286000	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
CY2022Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	12805887000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	12805887000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	13100000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	962152000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	11856835000	usd
CY2022Q4	mkl	Shortterm Investments Availablefor Sale Amortized Cost Basis ShorttermInvestmentsAvailableforSaleAmortizedCostBasis	2663560000	usd
CY2022Q4	mkl	Shortterm Investments Availablefor Sale Accumulated Gross Unrealized Gain Before Tax ShorttermInvestmentsAvailableforSaleAccumulatedGrossUnrealizedGainBeforeTax	5760000	usd
CY2022Q4	mkl	Shortterm Investments Availablefor Sale Accumulated Gross Unrealized Loss Before Tax ShorttermInvestmentsAvailableforSaleAccumulatedGrossUnrealizedLossBeforeTax	58000	usd
CY2022Q4	mkl	Shortterm Investments Availablefor Sale ShorttermInvestmentsAvailableforSale	2669262000	usd
CY2022Q4	mkl	Investments Availablefor Sale Amortized Cost Basis InvestmentsAvailableforSaleAmortizedCostBasis	15469447000	usd
CY2022Q4	mkl	Investments Availablefor Sale Accumulated Gross Unrealized Gain Before Tax InvestmentsAvailableforSaleAccumulatedGrossUnrealizedGainBeforeTax	18860000	usd
CY2022Q4	mkl	Investments Availablefor Sale Accumulated Gross Unrealized Loss Before Tax InvestmentsAvailableforSaleAccumulatedGrossUnrealizedLossBeforeTax	962210000	usd
CY2022Q4	mkl	Investments Availablefor Sale InvestmentsAvailableforSale	14526097000	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	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
CY2022Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position Lessthan12 Months ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPositionLessthan12Months	774480000	usd
CY2022Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position Lessthan12 Months Accumulated Loss ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss	-58000	usd
CY2022Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position12 Monthsor Longer ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPosition12MonthsorLonger	0	usd
CY2022Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position12 Monthsor Longer Accumulated Loss ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss	0	usd
CY2022Q4	mkl	Shortterm Investments Availableforsale Unrealized Loss Position Total ShorttermInvestmentsAvailableforsaleUnrealizedLossPositionTotal	774480000	usd
CY2022Q4	mkl	Shortterm Investments Availableforsale Unrealized Loss Position Accumulated Loss ShorttermInvestmentsAvailableforsaleUnrealizedLossPositionAccumulatedLoss	-58000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	7924623000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	568299000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	3356273000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	393911000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	11280896000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	962210000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	1400	securities
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	11300000000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	962200000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	1400	securities
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	246	securities
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	3400000000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	393900000	usd
CY2023Q4	mkl	Investments Available For Sale Allowance For Credit Loss InvestmentsAvailableForSaleAllowanceForCreditLoss	0	usd
CY2022Q4	mkl	Investments Available For Sale Allowance For Credit Loss InvestmentsAvailableForSaleAllowanceForCreditLoss	0	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	1192021000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	1179344000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	5033324000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	4917770000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	4320467000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	4159846000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	1523119000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	1401692000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	12068931000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate	11658652000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	14932286000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	14372732000	usd
CY2023	mkl	Estimated Average Duration Of Fixed Maturities EstimatedAverageDurationOfFixedMaturities	P4Y1M6D
CY2023	us-gaap	Investment Income Dividend InvestmentIncomeDividend	116911000	usd
CY2022	us-gaap	Investment Income Dividend InvestmentIncomeDividend	107213000	usd
CY2021	us-gaap	Investment Income Dividend InvestmentIncomeDividend	98099000	usd
CY2023	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	751754000	usd
CY2022	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	464013000	usd
CY2021	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	384419000	usd
CY2023	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	17222000	usd
CY2022	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	17258000	usd
CY2021	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	17002000	usd
CY2023	us-gaap	Net Investment Income NetInvestmentIncome	734532000	usd
CY2022	us-gaap	Net Investment Income NetInvestmentIncome	446755000	usd
CY2021	us-gaap	Net Investment Income NetInvestmentIncome	367417000	usd
CY2023	mkl	Net Realized Investment Gains Losses NetRealizedInvestmentGainsLosses	-42177000	usd
CY2022	mkl	Net Realized Investment Gains Losses NetRealizedInvestmentGainsLosses	-40983000	usd
CY2021	mkl	Net Realized Investment Gains Losses NetRealizedInvestmentGainsLosses	37908000	usd
CY2023	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	34684000	usd
CY2022	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	-14884000	usd
CY2021	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	25902000	usd
CY2023	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	1531547000	usd
CY2022	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-1539866000	usd
CY2021	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	1914724000	usd
CY2023	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	1566231000	usd
CY2022	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	-1554750000	usd
CY2021	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	1940626000	usd
CY2023	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1524054000	usd
CY2022	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	-1595733000	usd
CY2021	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1978534000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	390558000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-1463876000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-513084000	usd
CY2023Q4	mkl	Restricted Fixed Maturity Securities RestrictedFixedMaturitySecurities	3102899000	usd
CY2022Q4	mkl	Restricted Fixed Maturity Securities RestrictedFixedMaturitySecurities	2773386000	usd
CY2023Q4	mkl	Restricted Equity Securities RestrictedEquitySecurities	1004347000	usd
CY2022Q4	mkl	Restricted Equity Securities RestrictedEquitySecurities	843719000	usd
CY2023Q4	mkl	Restricted Short Term Investments RestrictedShortTermInvestments	807138000	usd
CY2022Q4	mkl	Restricted Short Term Investments RestrictedShortTermInvestments	543737000	usd
CY2023Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	584974000	usd
CY2022Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	1084081000	usd
CY2023Q4	us-gaap	Restricted Cash And Investments RestrictedCashAndInvestments	5499358000	usd
CY2022Q4	us-gaap	Restricted Cash And Investments RestrictedCashAndInvestments	5244923000	usd
CY2023Q4	us-gaap	Restricted Cash And Investments RestrictedCashAndInvestments	5499358000	usd
CY2022Q4	us-gaap	Restricted Cash And Investments RestrictedCashAndInvestments	5244923000	usd
CY2023	mkl	Percentage Threshold Of Shareholders Equity Used To Define Concentration Of Investments PercentageThresholdOfShareholdersEquityUsedToDefineConcentrationOfInvestments	0.10
CY2022	mkl	Percentage Threshold Of Shareholders Equity Used To Define Concentration Of Investments PercentageThresholdOfShareholdersEquityUsedToDefineConcentrationOfInvestments	0.10
CY2022Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	899000	usd
CY2021Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	56472000	usd
CY2023	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchases FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases	0	usd
CY2022	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchases FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases	0	usd
CY2023	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales	0	usd
CY2022	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales	56335000	usd
CY2023	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	95000	usd
CY2022	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	762000	usd
CY2023Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	994000	usd
CY2022Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	899000	usd
CY2023Q4	us-gaap	Equity Method Investments EquityMethodInvestments	605900000	usd
CY2022Q4	us-gaap	Equity Method Investments EquityMethodInvestments	494000000	usd
CY2023	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-2100000	usd
CY2022	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-22900000	usd
CY2021	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	15000000	usd
CY2023Q4	us-gaap	Accounts Receivable Gross AccountsReceivableGross	3486395000	usd
CY2022Q4	us-gaap	Accounts Receivable Gross AccountsReceivableGross	2983173000	usd
CY2023Q4	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	31089000	usd
CY2022Q4	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	22117000	usd
CY2023Q4	us-gaap	Premiums And Other Receivables Net PremiumsAndOtherReceivablesNet	3455306000	usd
CY2022Q4	us-gaap	Premiums And Other Receivables Net PremiumsAndOtherReceivablesNet	2961056000	usd
CY2021Q4	us-gaap	Goodwill Goodwill	2899140000	usd
CY2022	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	41905000	usd
CY2022	mkl	Goodwill Disposed Of During Period GoodwillDisposedOfDuringPeriod	-132455000	usd
CY2022	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	80000000	usd
CY2022	mkl	Goodwill Adjustments To Preliminary Purchase Price Allocation GoodwillAdjustmentsToPreliminaryPurchasePriceAllocation	-83358000	usd
CY2022	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	-6394000	usd
CY2022Q4	us-gaap	Goodwill Goodwill	2638838000	usd
CY2023	mkl	Goodwill Adjustments To Preliminary Purchase Price Allocation GoodwillAdjustmentsToPreliminaryPurchasePriceAllocation	-16752000	usd
CY2023	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	2663000	usd
CY2023Q4	us-gaap	Goodwill Goodwill	2624749000	usd
CY2022Q4	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	190600000	usd
CY2023Q4	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	190600000	usd
CY2023	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	usd
CY2022	us-gaap	Impairment Of Intangible Assets Excluding Goodwill ImpairmentOfIntangibleAssetsExcludingGoodwill	0	usd
CY2021	us-gaap	Impairment Of Intangible Assets Excluding Goodwill ImpairmentOfIntangibleAssetsExcludingGoodwill	0	usd
CY2023	us-gaap	Impairment Of Intangible Assets Excluding Goodwill ImpairmentOfIntangibleAssetsExcludingGoodwill	0	usd
CY2021Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	1822486000	usd
CY2022	mkl	Intangible Assets Acquired During Period IntangibleAssetsAcquiredDuringPeriod	21614000	usd
CY2022	mkl	Intangible Assets Disposed During Period IntangibleAssetsDisposedDuringPeriod	-2716000	usd
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	178778000	usd
CY2022	mkl	Intangible Assets Adjustments To Preliminary Purchase Price Allocation IntangibleAssetsAdjustmentsToPreliminaryPurchasePriceAllocation	86773000	usd
CY2022	us-gaap	Finite Lived Intangible Assets Translation And Purchase Accounting Adjustments FiniteLivedIntangibleAssetsTranslationAndPurchaseAccountingAdjustments	-1915000	usd
CY2022Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	1747464000	usd
CY2023	mkl	Intangible Assets Disposed During Period IntangibleAssetsDisposedDuringPeriod	-2000000	usd
CY2023	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	180614000	usd
CY2023	mkl	Intangible Assets Adjustments To Preliminary Purchase Price Allocation IntangibleAssetsAdjustmentsToPreliminaryPurchasePriceAllocation	22671000	usd
CY2023	us-gaap	Finite Lived Intangible Assets Translation And Purchase Accounting Adjustments FiniteLivedIntangibleAssetsTranslationAndPurchaseAccountingAdjustments	1163000	usd
CY2023Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	1588684000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	175700000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	169000000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	160600000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	150700000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	140800000	usd
CY2023Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	90400000	usd
CY2022Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	92400000	usd
CY2023Q4	us-gaap	Intangible Assets Gross Excluding Goodwill IntangibleAssetsGrossExcludingGoodwill	2860728000	usd
CY2023Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	1272044000	usd
CY2022Q4	us-gaap	Intangible Assets Gross Excluding Goodwill IntangibleAssetsGrossExcludingGoodwill	2836774000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	1089310000	usd
CY2023	mkl	Lease Of Facilities And Furniture Maximum Duration LeaseOfFacilitiesAndFurnitureMaximumDuration	P19Y
CY2023	us-gaap	Operating Lease Expense OperatingLeaseExpense	148400000	usd
CY2022	us-gaap	Operating Lease Expense OperatingLeaseExpense	126300000	usd
CY2021	us-gaap	Operating Lease Expense OperatingLeaseExpense	115400000	usd
CY2023Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	628833000	usd
CY2022Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	526704000	usd
CY2023Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	657217000	usd
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	554394000	usd
CY2023Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P9Y9M18D
CY2022Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P11Y8M12D
CY2023Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.052
CY2022Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.031
CY2023	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	130200000	usd
CY2022	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	64400000	usd
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	37600000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	125845000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	107119000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	89952000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	74683000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	65133000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	347168000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	809900000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	152683000	usd
CY2023Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	657217000	usd
CY2023	us-gaap	Lease Income LeaseIncome	188904000	usd
CY2022	us-gaap	Lease Income LeaseIncome	157552000	usd
CY2021	us-gaap	Lease Income LeaseIncome	99994000	usd
CY2023	mkl	Revenues From Program Services And Other Fronting RevenuesFromProgramServicesAndOtherFronting	154838000	usd
CY2022	mkl	Revenues From Program Services And Other Fronting RevenuesFromProgramServicesAndOtherFronting	147612000	usd
CY2021	mkl	Revenues From Program Services And Other Fronting RevenuesFromProgramServicesAndOtherFronting	123823000	usd
CY2023	mkl	Equity Method And Other Investments Income Loss EquityMethodAndOtherInvestmentsIncomeLoss	-13598000	usd
CY2022	mkl	Equity Method And Other Investments Income Loss EquityMethodAndOtherInvestmentsIncomeLoss	-15120000	usd
CY2021	mkl	Equity Method And Other Investments Income Loss EquityMethodAndOtherInvestmentsIncomeLoss	13317000	usd
CY2023	us-gaap	Other Nonrecurring Gain OtherNonrecurringGain	16923000	usd
CY2022	us-gaap	Other Nonrecurring Gain OtherNonrecurringGain	225828000	usd
CY2021	us-gaap	Other Nonrecurring Gain OtherNonrecurringGain	0	usd
CY2023	mkl	Other Revenues Losses OtherRevenuesLosses	42733000	usd
CY2022	mkl	Other Revenues Losses OtherRevenuesLosses	33970000	usd
CY2021	mkl	Other Revenues Losses OtherRevenuesLosses	33727000	usd
CY2023	mkl	Products Revenues And Services And Other Revenues ProductsRevenuesAndServicesAndOtherRevenues	5249565000	usd
CY2022	mkl	Products Revenues And Services And Other Revenues ProductsRevenuesAndServicesAndOtherRevenues	5236521000	usd
CY2021	mkl	Products Revenues And Services And Other Revenues ProductsRevenuesAndServicesAndOtherRevenues	3997445000	usd
CY2023	us-gaap	Schedule Of Liability For Unpaid Claims And Claims Adjustment Expense ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense	The following table presents a reconciliation of consolidated beginning and ending reserves for losses and loss adjustment expenses.<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:59.224%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:11.731%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.389%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:11.731%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.389%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:11.736%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="15" 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%">Years Ended December 31,</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%">2023</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%">2022</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%">2021</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%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">20,947,898</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</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%">18,178,894 </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%">16,222,376 </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%">7,994,884</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%">6,876,317 </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%">5,736,659 </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%">12,953,014</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%">11,302,577 </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%">10,485,717 </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%">70,344</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%">(160,622)</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%">(54,736)</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%">13,023,358</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%">11,141,955 </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%">10,430,981 </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><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%">5,360,559</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%">4,613,035 </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%">4,061,000 </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%">(38,550)</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%">(167,446)</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%">(478,930)</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%">5,322,009</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%">4,445,589 </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%">3,582,070 </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><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%">729,895</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%">580,537 </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%">637,169 </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%">2,663,165</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%">2,396,446 </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%">2,066,290 </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%">3,393,060</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%">2,976,983 </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%">2,703,459 </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%">(1,532)</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%">(5,468)</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%">(4,253)</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 17)</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%">(162,954)</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%">347,921 </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%">— </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%">Net reserves for losses and loss adjustment expenses of insurance companies sold</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%">— </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%">(2,762)</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%">Reinsurance recoverable on retroactive reinsurance transactions</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%">(125,067)</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%">— </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%">— </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%">Net reserves for losses and loss adjustment expenses, end of year</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%">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:#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%">12,953,014 </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%">11,302,577 </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%">Reinsurance recoverables on unpaid losses, end of year</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%">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:#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%">7,994,884 </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%">6,876,317 </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%">Gross reserves for losses and loss adjustment expenses, end of year</span></td><td style="background-color:#ffffff;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:#ffffff;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%">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:#ffffff;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:#ffffff;padding:0 1pt"></td><td style="background-color:#ffffff;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%">$</span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">20,947,898 </span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#ffffff;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%">18,178,894 </span></td><td style="background-color:#ffffff;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>
CY2022Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	20947898000	usd
CY2021Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	18178894000	usd
CY2020Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	16222376000	usd
CY2022Q4	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	7994884000	usd
CY2021Q4	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	6876317000	usd
CY2020Q4	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	5736659000	usd
CY2022Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	12953014000	usd
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	11302577000	usd
CY2020Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	10485717000	usd
CY2023Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	70344000	usd
CY2022Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	-160622000	usd
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	-54736000	usd
CY2023Q4	mkl	Adjusted Liability For Unpaid Claims And Claims Adjustment Expense Net AdjustedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	13023358000	usd
CY2022Q4	mkl	Adjusted Liability For Unpaid Claims And Claims Adjustment Expense Net AdjustedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	11141955000	usd
CY2021Q4	mkl	Adjusted Liability For Unpaid Claims And Claims Adjustment Expense Net AdjustedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	10430981000	usd
CY2023	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	5360559000	usd
CY2022	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	4613035000	usd
CY2021	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	4061000000	usd
CY2023	mkl	Prior Year Claims And Claim Adjustment Expense Including Deposit Liab PriorYearClaimsAndClaimAdjustmentExpenseIncludingDepositLiab	-38550000	usd
CY2022	mkl	Prior Year Claims And Claim Adjustment Expense Including Deposit Liab PriorYearClaimsAndClaimAdjustmentExpenseIncludingDepositLiab	-167446000	usd
CY2021	mkl	Prior Year Claims And Claim Adjustment Expense Including Deposit Liab PriorYearClaimsAndClaimAdjustmentExpenseIncludingDepositLiab	-478930000	usd
CY2023	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	5322009000	usd
CY2022	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	4445589000	usd
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	3582070000	usd
CY2023	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	729895000	usd
CY2022	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	580537000	usd
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	637169000	usd
CY2023	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	2663165000	usd
CY2022	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	2396446000	usd
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	2066290000	usd
CY2023	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	3393060000	usd
CY2022	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	2976983000	usd
CY2021	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	2703459000	usd
CY2023	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Currency Translation Gain Loss LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCurrencyTranslationGainLoss	-1532000	usd
CY2022	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Currency Translation Gain Loss LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCurrencyTranslationGainLoss	-5468000	usd
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Currency Translation Gain Loss LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCurrencyTranslationGainLoss	-4253000	usd
CY2023	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Business Acquisitions LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitions	-162954000	usd
CY2022	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Business Acquisitions LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitions	347921000	usd
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Business Acquisitions LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitions	0	usd
CY2023	mkl	Liability For Unpaid Claims And Claims Adjustment Expenses Business Disposal LiabilityForUnpaidClaimsAndClaimsAdjustmentExpensesBusinessDisposal	0	usd
CY2022	mkl	Liability For Unpaid Claims And Claims Adjustment Expenses Business Disposal LiabilityForUnpaidClaimsAndClaimsAdjustmentExpensesBusinessDisposal	0	usd
CY2021	mkl	Liability For Unpaid Claims And Claims Adjustment Expenses Business Disposal LiabilityForUnpaidClaimsAndClaimsAdjustmentExpensesBusinessDisposal	-2762000	usd
CY2023	mkl	Reinsurance Recoverable Retroactive Reinsurance Transaction ReinsuranceRecoverableRetroactiveReinsuranceTransaction	-125067000	usd
CY2022	mkl	Reinsurance Recoverable Retroactive Reinsurance Transaction ReinsuranceRecoverableRetroactiveReinsuranceTransaction	0	usd
CY2021	mkl	Reinsurance Recoverable Retroactive Reinsurance Transaction ReinsuranceRecoverableRetroactiveReinsuranceTransaction	0	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
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	11302577000	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
CY2021Q4	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	6876317000	usd
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
CY2021Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	18178894000	usd
CY2023Q4	mkl	Ibnr Reserves Percentage Of Total Unpaid Losses And Loss Adjustment Expenses IBNRReservesPercentageOfTotalUnpaidLossesAndLossAdjustmentExpenses	0.72
CY2022Q4	mkl	Ibnr Reserves Percentage Of Total Unpaid Losses And Loss Adjustment Expenses IBNRReservesPercentageOfTotalUnpaidLossesAndLossAdjustmentExpenses	0.70
CY2023	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-38600000	usd
CY2022	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-167400000	usd
CY2021	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-479800000	usd
CY2023Q4	us-gaap	Shortduration Insurance Contracts Liability For Unpaid Claims And Allocated Claim Adjustment Expense Net ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet	14284815000	usd
CY2023Q4	us-gaap	Reinsurance Recoverable For Unpaid Claims And Claims Adjustments ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments	8820567000	usd
CY2023Q4	us-gaap	Shortduration Insurance Contracts Liability For Unpaid Claims And Claims Adjustment Expense Accumulated Unallocated Claim Adjustment Expense ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAccumulatedUnallocatedClaimAdjustmentExpense	377939000	usd
CY2023Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	23483321000	usd
CY2023	us-gaap	Direct Premiums Written DirectPremiumsWritten	11306483000	usd
CY2023	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	2695754000	usd
CY2023	us-gaap	Ceded Premiums Written CededPremiumsWritten	5604662000	usd
CY2023	us-gaap	Premiums Written Net PremiumsWrittenNet	8397575000	usd
CY2023	us-gaap	Direct Premiums Earned DirectPremiumsEarned	10999889000	usd
CY2023	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	2554030000	usd
CY2023	us-gaap	Ceded Premiums Earned CededPremiumsEarned	5258440000	usd
CY2023	us-gaap	Premiums Earned Net PremiumsEarnedNet	8295479000	usd
CY2022	us-gaap	Direct Premiums Written DirectPremiumsWritten	10729950000	usd
CY2022	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	2471732000	usd
CY2022	us-gaap	Ceded Premiums Written CededPremiumsWritten	4998292000	usd
CY2022	us-gaap	Premiums Written Net PremiumsWrittenNet	8203390000	usd
CY2022	us-gaap	Direct Premiums Earned DirectPremiumsEarned	10068570000	usd
CY2022	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	2246805000	usd
CY2022	us-gaap	Ceded Premiums Earned CededPremiumsEarned	4727583000	usd
CY2022	us-gaap	Premiums Earned Net PremiumsEarnedNet	7587792000	usd
CY2021	us-gaap	Direct Premiums Written DirectPremiumsWritten	9508184000	usd
CY2021	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	1930498000	usd
CY2021	us-gaap	Ceded Premiums Written CededPremiumsWritten	4318951000	usd
CY2021	us-gaap	Premiums Written Net PremiumsWrittenNet	7119731000	usd
CY2021	us-gaap	Direct Premiums Earned DirectPremiumsEarned	8729068000	usd
CY2021	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	1744346000	usd
CY2021	us-gaap	Ceded Premiums Earned CededPremiumsEarned	3970385000	usd
CY2021	us-gaap	Premiums Earned Net PremiumsEarnedNet	6503029000	usd
CY2023	mkl	Premiums Percentage Ceded To Gross PremiumsPercentageCededToGross	0.39
CY2022	mkl	Premiums Percentage Ceded To Gross PremiumsPercentageCededToGross	0.38
CY2021	mkl	Premiums Percentage Ceded To Gross PremiumsPercentageCededToGross	0.38
CY2021	us-gaap	Liability For Future Policy Benefits Payment For Benefits LiabilityForFuturePolicyBenefitsPaymentForBenefits	60277000	usd
CY2023Q4	mkl	Liability For Future Policy Benefit Expected Future Policy Benefit Effect Of Foreign Currency Rate Changes LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitEffectOfForeignCurrencyRateChanges	18705000	usd
CY2022Q4	mkl	Liability For Future Policy Benefit Expected Future Policy Benefit Effect Of Foreign Currency Rate Changes LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitEffectOfForeignCurrencyRateChanges	-36086000	usd
CY2021Q4	mkl	Liability For Future Policy Benefit Expected Future Policy Benefit Effect Of Foreign Currency Rate Changes LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitEffectOfForeignCurrencyRateChanges	-46235000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefit Expected Future Benefit Original Discount Rate Before Reinsurance After Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange	642877000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefit Expected Future Benefit Original Discount Rate Before Reinsurance After Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange	667761000	usd
CY2021Q4	us-gaap	Liability For Future Policy Benefit Expected Future Benefit Original Discount Rate Before Reinsurance After Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange	745313000	usd
CY2023Q4	us-gaap	Aoci Liability For Future Policy Benefit Expected Future Policy Benefit Before Tax AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax	-85114000	usd
CY2023	us-gaap	Premiums Percentage Assumed To Net PremiumsPercentageAssumedToNet	0.31
CY2022	us-gaap	Premiums Percentage Assumed To Net PremiumsPercentageAssumedToNet	0.30
CY2021	us-gaap	Premiums Percentage Assumed To Net PremiumsPercentageAssumedToNet	0.27
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	mkl	Liability For Future Policy Benefit Deferred Profit Liability LiabilityForFuturePolicyBenefitDeferredProfitLiability	52287000	usd
CY2022Q4	mkl	Liability For Future Policy Benefit Deferred Profit Liability LiabilityForFuturePolicyBenefitDeferredProfitLiability	48569000	usd
CY2023Q4	mkl	Liability For Future Policy Benefit Expected Future Policy Benefit Other LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOther	39004000	usd
CY2022Q4	mkl	Liability For Future Policy Benefit Expected Future Policy Benefit Other LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOther	47786000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	649054000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	650721000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Undiscounted Before Reinsurance LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance	824600000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Undiscounted Before Reinsurance LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance	861300000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Before Reinsurance After Discount Rate Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange	554366000	usd
CY2021Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Before Reinsurance After Discount Rate Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange	821632000	usd
CY2020Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Before Reinsurance After Discount Rate Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange	976905000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Original Discount Rate Before Cash Flow And Reinsurance LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance	667761000	usd
CY2021Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Original Discount Rate Before Cash Flow And Reinsurance LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance	745313000	usd
CY2020Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Original Discount Rate Before Cash Flow And Reinsurance LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance	838041000	usd
CY2022Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Cumulative Increase Decrease From Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange	0	usd
CY2021Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Cumulative Increase Decrease From Cash Flow Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange	0	usd
CY2020Q4	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 Of Actual Variance From Expected Experience LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience	-5890000	usd
CY2021Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Cumulative Increase Decrease Of Actual Variance From Expected Experience LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience	-3859000	usd
CY2020Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Cumulative Increase Decrease Of Actual Variance From Expected Experience LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience	-4208000	usd
CY2022Q4	mkl	Adjusted Liability For Future Policyholder Benefits Beginning Of Year AdjustedLiabilityForFuturePolicyholderBenefitsBeginningOfYear	661871000	usd
CY2021Q4	mkl	Adjusted Liability For Future Policyholder Benefits Beginning Of Year AdjustedLiabilityForFuturePolicyholderBenefitsBeginningOfYear	741454000	usd
CY2020Q4	mkl	Adjusted Liability For Future Policyholder Benefits Beginning Of Year AdjustedLiabilityForFuturePolicyholderBenefitsBeginningOfYear	833833000	usd
CY2023	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Interest Expense LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense	14889000	usd
CY2022	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Interest Expense LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense	15625000	usd
CY2021	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Interest Expense LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense	17992000	usd
CY2023	us-gaap	Liability For Future Policy Benefits Payment For Benefits LiabilityForFuturePolicyBenefitsPaymentForBenefits	52588000	usd
CY2022	us-gaap	Liability For Future Policy Benefits Payment For Benefits LiabilityForFuturePolicyBenefitsPaymentForBenefits	53232000	usd
CY2022Q4	us-gaap	Aoci Liability For Future Policy Benefit Expected Future Policy Benefit Before Tax AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax	-113395000	usd
CY2021Q4	us-gaap	Aoci Liability For Future Policy Benefit Expected Future Policy Benefit Before Tax AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax	76319000	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
CY2021Q4	us-gaap	Liability For Future Policy Benefit Expected Future Policy Benefit Before Reinsurance After Discount Rate Change LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange	821632000	usd
CY2023Q4	us-gaap	Liability For Future Policy Benefit Weighted Average Interest Accretion Rate LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate	0.023	rate
CY2022Q4	us-gaap	Liability For Future Policy Benefit Weighted Average Interest Accretion Rate LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate	0.023	rate
CY2023Q4	us-gaap	Liability For Future Policy Benefit Current Weighted Average Discount Rate LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate	0.038	rate
CY2022Q4	us-gaap	Liability For Future Policy Benefit Current Weighted Average Discount Rate LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate	0.043	rate
CY2023Q4	us-gaap	Liability For Future Policy Benefit Weighted Average Duration LiabilityForFuturePolicyBenefitWeightedAverageDuration	P8Y7M6D
CY2022Q4	us-gaap	Liability For Future Policy Benefit Weighted Average Duration LiabilityForFuturePolicyBenefitWeightedAverageDuration	P8Y7M6D
CY2023Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	3779796000	usd
CY2022Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	4103629000	usd
CY2023Q4	us-gaap	Debt Instrument Fair Value DebtInstrumentFairValue	3400000000	usd
CY2022Q4	us-gaap	Debt Instrument Fair Value DebtInstrumentFairValue	3500000000	usd
CY2023Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	76150000	usd
CY2023Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	28944000	usd
CY2023Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	28567000	usd
CY2023Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	454386000	usd
CY2023Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	16178000	usd
CY2023Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	3219484000	usd
CY2023Q4	mkl	Long Term Debt Maturities Total Future Repayments Of Principal LongTermDebtMaturitiesTotalFutureRepaymentsOfPrincipal	3823709000	usd
CY2023Q4	us-gaap	Debt Instrument Unamortized Discount Premium Net DebtInstrumentUnamortizedDiscountPremiumNet	35585000	usd
CY2023Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	8328000	usd
CY2023	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	552616000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-48209000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	683961000	usd
CY2023	us-gaap	Income Taxes Paid IncomeTaxesPaid	280700000	usd
CY2023Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	3779796000	usd
CY2023	us-gaap	Interest Paid InterestPaid	187800000	usd
CY2022	us-gaap	Interest Paid InterestPaid	197300000	usd
CY2021	us-gaap	Interest Paid InterestPaid	178600000	usd
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1711849000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	-109311000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	2263748000	usd
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	941857000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	-42255000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	866080000	usd
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	2653706000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-151566000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	3129828000	usd
CY2023	us-gaap	Current Federal State And Local Tax Expense Benefit CurrentFederalStateAndLocalTaxExpenseBenefit	249149000	usd
CY2022	us-gaap	Current Federal State And Local Tax Expense Benefit CurrentFederalStateAndLocalTaxExpenseBenefit	222074000	usd
CY2021	us-gaap	Current Federal State And Local Tax Expense Benefit CurrentFederalStateAndLocalTaxExpenseBenefit	200742000	usd
CY2023	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	69669000	usd
CY2022	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	12042000	usd
CY2021	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	29811000	usd
CY2023	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	318818000	usd
CY2022	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	234116000	usd
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	230553000	usd
CY2023	us-gaap	Deferred Federal State And Local Tax Expense Benefit DeferredFederalStateAndLocalTaxExpenseBenefit	250041000	usd
CY2022	us-gaap	Deferred Federal State And Local Tax Expense Benefit DeferredFederalStateAndLocalTaxExpenseBenefit	-301423000	usd
CY2021	us-gaap	Deferred Federal State And Local Tax Expense Benefit DeferredFederalStateAndLocalTaxExpenseBenefit	437743000	usd
CY2023	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	-16243000	usd
CY2022	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	19098000	usd
CY2021	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	15665000	usd
CY2023	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	233798000	usd
CY2022	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-282325000	usd
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	453408000	usd
CY2022	us-gaap	Income Taxes Paid IncomeTaxesPaid	251500000	usd
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CY2023	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1960060000	usd
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CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-23.72
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	176.79
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CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-23.72
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	176.38
CY2023Q4	mkl	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Issuance ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForIssuance	86144	shares
CY2023Q4	mkl	Funds At Lloyds FundsAtLloyds	1000000000	usd
CY2023Q4	ecd	Rule10b51 Arr Adopted Flag Rule10b51ArrAdoptedFlag	false
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CY2023	dei	Auditor Name AuditorName	KPMG LLP
CY2023	dei	Auditor Location AuditorLocation	Richmond, VA
CY2023	dei	Auditor Firm AuditorFirmId	185

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$MKL
MARKEL GROUP INC. Stock $mkl

2024 Q1 Form 10-K Financial Statement

#000109634324000025 Filed on February 23, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$MKL MARKEL GROUP INC. Stock $mkl

2024 Q1 Form 10-K Financial Statement

#000109634324000025 Filed on February 23, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$MKL
MARKEL GROUP INC. Stock $mkl