$MKL
MARKEL GROUP INC. Stock $mkl

$mkl Overview Financials Valuation SEC Filings Company Website

2019 Q4 Form 10-K Financial Statement

#000109634320000039 Filed on February 21, 2020

Income Statement

Concept	2019 Q4	2019	2018 Q4
Revenue	$2.582B	$9.526B	$1.043B
YoY Change	147.55%	39.25%	-37.26%
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	$36.00M	$1.100B	$29.70M
YoY Change	21.21%	1260.32%	8.79%
% of Gross Profit
Operating Expenses	$1.828B	$7.049B	$1.975B
YoY Change	-7.46%	6.76%	33.12%
Operating Profit		$2.477B
YoY Change		6130.91%
Interest Expense	-$101.9M	$171.7M	$1.700M
YoY Change	-6094.12%	11.33%	-104.86%
% of Operating Profit		6.93%
Other Income/Expense, Net
YoY Change
Pretax Income	$641.0M	$2.286B	-$930.5M
YoY Change	-168.89%	-29200.04%	-747.53%
Income Tax	$129.5M	$486.3M	-$177.1M
% Of Pretax Income	20.2%	21.28%
Net Earnings	$511.1M	$1.790B	-$751.5M
YoY Change	-168.01%	-1496.84%	-272.82%
Net Earnings / Revenue	19.8%	18.8%	-72.07%
Basic Earnings Per Share	$36.34	$129.30	-$53.88
Diluted Earnings Per Share	$36.26	$129.10	-$53.88
COMMON SHARES
Basic Shares Outstanding	13.81M shares	13.86M shares	13.88M shares
Diluted Shares Outstanding		13.88M shares

Balance Sheet

Concept	2019 Q4	2019	2018 Q4
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$3.073B	$3.073B	$2.014B
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory	$303.1M		$298.7M
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$588.6M	$821.0M	$551.5M
YoY Change	6.73%	48.73%	9.94%
Goodwill	$2.309B		$2.238B
YoY Change	3.15%		25.91%
Intangibles	$1.738B		$1.726B
YoY Change	0.71%		27.33%
Long-Term Investments	$18.76B	$18.76B	$16.84B
YoY Change	11.38%	11.38%	-6.79%
Other Assets	$428.0M	$450.0M	$382.0M
YoY Change	12.04%	17.8%	26.49%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$37.47B	$37.47B	$33.31B
YoY Change	12.51%	12.51%	1.53%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$262.0M	$262.0M
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due		$64.00M
YoY Change		-77.85%
Total Short-Term Liabilities	$262.0M	$326.0M
YoY Change		12.8%
LONG-TERM LIABILITIES
Long-Term Debt	$3.534B	$3.471B	$3.010B
YoY Change	17.41%	27.56%	-2.87%
Other Long-Term Liabilities	$3.228B	$2.345B	$2.797B
YoY Change	15.41%	-16.16%	-0.85%
Total Long-Term Liabilities	$6.762B	$5.816B	$5.807B
YoY Change	16.45%	5.4%	-1.91%
TOTAL LIABILITIES
Total Short-Term Liabilities	$262.0M	$326.0M
Total Long-Term Liabilities	$6.762B	$5.816B	$5.807B
Total Liabilities	$26.22B	$26.40B	$24.03B
YoY Change	9.1%	8.99%	3.87%
SHAREHOLDERS EQUITY
Retained Earnings	$7.457B		$5.782B
YoY Change	28.97%		53.1%
Common Stock	$3.405B		$3.393B
YoY Change	0.35%		0.33%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$11.07B	$11.07B	$9.081B
YoY Change
Total Liabilities & Shareholders Equity	$37.47B	$37.47B	$33.31B
YoY Change	12.51%	12.51%	1.53%

Cashflow Statement

Concept	2019 Q4	2019	2018 Q4
OPERATING ACTIVITIES
Net Income	$511.1M	$1.790B	-$751.5M
YoY Change	-168.01%	-1496.84%	-272.82%
Depreciation, Depletion And Amortization	$36.00M	$1.100B	$29.70M
YoY Change	21.21%	1260.32%	8.79%
Cash From Operating Activities	$562.1M	$1.274B	$129.7M
YoY Change	333.38%	42.7%	-50.08%
INVESTING ACTIVITIES
Capital Expenditures	-$27.90M	$123.4M	-$27.70M
YoY Change	0.72%	15.74%	12.6%
Acquisitions		$245.3M
YoY Change		-79.12%
Other Investing Activities	$149.9M	-$16.80M	-$316.3M
YoY Change	-147.39%	-150.43%	-49.45%
Cash From Investing Activities	$122.0M	-$535.2M	-$344.0M
YoY Change	-135.47%	-32.87%	-47.1%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net		$116.3M
YoY Change		115.36%
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-411.3M	$359.3M	-7.200M
YoY Change	5612.5%	-300.75%	-101.3%
NET CHANGE
Cash From Operating Activities	562.1M	$1.274B	129.7M
Cash From Investing Activities	122.0M	-$535.2M	-344.0M
Cash From Financing Activities	-411.3M	$359.3M	-7.200M
Net Change In Cash	272.8M	$1.104B	-221.5M
YoY Change	-223.16%	-1157.25%	-234.16%
FREE CASH FLOW
Cash From Operating Activities	$562.1M	$1.274B	$129.7M
Capital Expenditures	-$27.90M	$123.4M	-$27.70M
Free Cash Flow	$590.0M	$1.151B	$157.4M
YoY Change	274.84%	46.36%	-44.66%

Facts In Submission

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CY2019	dei	Document Transition Report DocumentTransitionReport	false
CY2019	dei	Entity Central Index Key EntityCentralIndexKey	0001096343
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CY2019	dei	Document Type DocumentType	10-K
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CY2019	dei	Entity Registrant Name EntityRegistrantName	MARKEL CORPORATION
CY2019	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	VA
CY2019	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	54-1959284
CY2019	dei	Entity Address Address Line1 EntityAddressAddressLine1	4521 Highwoods Parkway
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CY2017	us-gaap	Profit Loss ProfitLoss	400758000	USD
CY2019	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	8996000	USD
CY2018	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	-2173000	USD
CY2017	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	5489000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1790466000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	-128180000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	395269000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	299125000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-241325000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	787339000	USD
CY2019	mkl	Reclassification Adjustments For Net Gains Losses Included In Net Income Loss ReclassificationAdjustmentsForNetGainsLossesIncludedInNetIncomeLoss	1148000	USD
CY2018	mkl	Reclassification Adjustments For Net Gains Losses Included In Net Income Loss ReclassificationAdjustmentsForNetGainsLossesIncludedInNetIncomeLoss	-7849000	USD
CY2017	mkl	Reclassification Adjustments For Net Gains Losses Included In Net Income Loss ReclassificationAdjustmentsForNetGainsLossesIncludedInNetIncomeLoss	24296000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	297977000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-233476000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	763043000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	382000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	-16495000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	10449000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-5042000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-2341000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-6259000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	303401000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-247630000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	779751000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	2102863000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-377983000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	1180509000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	8975000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	-2213000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	5535000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	2093888000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-375770000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	1174974000	USD
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	129.25
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-9.55
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	25.89
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	129.07
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-9.55
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	25.81
CY2019	us-gaap	Profit Loss ProfitLoss	1799462000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	-130353000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	400758000	USD
CY2019	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	-323385000	USD
CY2018	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	-2729000	USD
CY2017	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	324090000	USD
CY2019	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	269239000	USD
CY2018	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	227846000	USD
CY2017	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	203871000	USD
CY2019	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	1601722000	USD
CY2018	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	-437596000	USD
CY2017	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	-5303000	USD
CY2019	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	-2265000	USD
CY2018	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	106598000	USD
CY2017	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	3140000	USD
CY2019	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	USD
CY2018	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	199198000	USD
CY2017	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	USD
CY2019	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	103982000	USD
CY2018	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	27961000	USD
CY2017	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	38259000	USD
CY2019	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	93015000	USD
CY2018	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	15585000	USD
CY2017	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	67923000	USD
CY2019	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	226263000	USD
CY2018	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	298796000	USD
CY2017	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	619305000	USD
CY2019	us-gaap	Increase Decrease In Life Insurance Liabilities IncreaseDecreaseInLifeInsuranceLiabilities	-52159000	USD
CY2018	us-gaap	Increase Decrease In Life Insurance Liabilities IncreaseDecreaseInLifeInsuranceLiabilities	-50541000	USD
CY2017	us-gaap	Increase Decrease In Life Insurance Liabilities IncreaseDecreaseInLifeInsuranceLiabilities	-55647000	USD
CY2019	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	354116000	USD
CY2018	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	62879000	USD
CY2017	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	197706000	USD
CY2019	us-gaap	Increase Decrease In Reinsurance Payables IncreaseDecreaseInReinsurancePayables	65460000	USD
CY2018	us-gaap	Increase Decrease In Reinsurance Payables IncreaseDecreaseInReinsurancePayables	-4313000	USD
CY2017	us-gaap	Increase Decrease In Reinsurance Payables IncreaseDecreaseInReinsurancePayables	-40761000	USD
CY2019	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	36938000	USD
CY2018	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	53730000	USD
CY2017	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	-35968000	USD
CY2019	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	24432000	USD
CY2018	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	-23756000	USD
CY2017	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	-71669000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-9528000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-5637000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	45051000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-32966000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	25173000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-23992000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1274120000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	892857000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	858529000	USD
CY2019	us-gaap	Proceeds From Sale Maturity And Collections Of Investments ProceedsFromSaleMaturityAndCollectionsOfInvestments	353918000	USD
CY2018	us-gaap	Proceeds From Sale Maturity And Collections Of Investments ProceedsFromSaleMaturityAndCollectionsOfInvestments	419199000	USD
CY2017	us-gaap	Proceeds From Sale Maturity And Collections Of Investments ProceedsFromSaleMaturityAndCollectionsOfInvestments	577650000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	772336000	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	551808000	USD
CY2017	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	1129895000	USD
CY2019	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	955970000	USD
CY2018	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	1545913000	USD
CY2017	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	1176281000	USD
CY2019	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	95867000	USD
CY2018	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	-1101636000	USD
CY2017	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	-234743000	USD
CY2019	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	257663000	USD
CY2018	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	8864000	USD
CY2017	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	13023000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	123376000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	106593000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	74652000	USD
CY2019	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	245332000	USD
CY2018	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	1175211000	USD
CY2017	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	1431712000	USD
CY2019	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-16795000	USD
CY2018	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	33301000	USD
CY2017	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-8923000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-535159000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-797239000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-744457000	USD
CY2019	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	1645182000	USD
CY2018	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	206949000	USD
CY2017	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	664657000	USD
CY2019	us-gaap	Repayments Of Debt RepaymentsOfDebt	1103674000	USD
CY2018	us-gaap	Repayments Of Debt RepaymentsOfDebt	289199000	USD
CY2017	us-gaap	Repayments Of Debt RepaymentsOfDebt	259972000	USD
CY2019	us-gaap	Payments Of Debt Extinguishment Costs PaymentsOfDebtExtinguishmentCosts	27073000	USD
CY2018	us-gaap	Payments Of Debt Extinguishment Costs PaymentsOfDebtExtinguishmentCosts	0	USD
CY2017	us-gaap	Payments Of Debt Extinguishment Costs PaymentsOfDebtExtinguishmentCosts	0	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	116307000	USD
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	54007000	USD
CY2017	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	110838000	USD
CY2019	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	14113000	USD
CY2018	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	15914000	USD
CY2017	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	5018000	USD
CY2019	us-gaap	Payments To Acquire Additional Interest In Subsidiaries PaymentsToAcquireAdditionalInterestInSubsidiaries	9754000	USD
CY2018	us-gaap	Payments To Acquire Additional Interest In Subsidiaries PaymentsToAcquireAdditionalInterestInSubsidiaries	13523000	USD
CY2017	us-gaap	Payments To Acquire Additional Interest In Subsidiaries PaymentsToAcquireAdditionalInterestInSubsidiaries	18334000	USD
CY2019	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	8992000	USD
CY2018	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	9164000	USD
CY2017	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	7899000	USD
CY2019	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-5952000	USD
CY2018	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-4127000	USD
CY2017	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-6281000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	359317000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-178985000	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	256315000	USD
CY2019	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	5643000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	2085164000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	3500353000	USD
CY2018	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-21047000	USD
CY2017	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	45295000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	1103921000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-104414000	USD
CY2017	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	415682000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	2396432000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	2500846000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	2396432000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	2500846000	USD
CY2019	us-gaap	Use Of Estimates UseOfEstimates	<span style="font-family:inherit;font-size:10pt;font-weight:bold;">Use of Estimates.</span><span style="font-family:inherit;font-size:10pt;"> 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, life and annuity reinsurance benefit reserves and litigation 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>
CY2019	mkl	Deferred Policy Acquisition Cost Amortization Period DeferredPolicyAcquisitionCostAmortizationPeriod	P1Y
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	588600000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	551500000	USD
CY2019Q4	us-gaap	Inventory Net InventoryNet	303100000	USD
CY2018Q4	us-gaap	Inventory Net InventoryNet	298700000	USD
CY2019	mkl	Tax Benefit Greater Than Fifty Percent TaxBenefitGreaterThanFiftyPercent	0.50
CY2019	mkl	Revenue Recognition Period Insurance Premiums RevenueRecognitionPeriodInsurancePremiums	P1Y
CY2019	mkl	Reinsurance Accounting Policy For Program Services ReinsuranceAccountingPolicyForProgramServices	<span style="font-family:inherit;font-size:10pt;font-weight:bold;">Program Services. </span><span style="font-family:inherit;font-size:10pt;">In connection with its program services business, the Company enters into contractual agreements with both producing general agents and reinsurers, whereby the general agents and reinsurers are typically obligated to each other for payment of insurance amounts, including premiums, commissions and losses. To the extent these funds are not the obligation of the Company and are settled directly between the general agent and the reinsurer, no receivables or payables are recorded for these amounts. All obligations of the Company's insurance subsidiaries owed to or on behalf of their policyholders are recorded by the Company and, to the extent appropriate, offsetting reinsurance recoverables are recorded.</span><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div>
CY2019	us-gaap	Allocated Share Based Compensation Expense Net Of Tax AllocatedShareBasedCompensationExpenseNetOfTax	24600000	USD
CY2018	us-gaap	Allocated Share Based Compensation Expense Net Of Tax AllocatedShareBasedCompensationExpenseNetOfTax	13000000.0	USD
CY2017	us-gaap	Allocated Share Based Compensation Expense Net Of Tax AllocatedShareBasedCompensationExpenseNetOfTax	11900000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	9448840000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	536488000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	14419000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	9970909000	USD
CY2019Q4	mkl	Shortterm Investments Availablefor Sale Amortized Cost Basis ShorttermInvestmentsAvailableforSaleAmortizedCostBasis	1194953000	USD
CY2019Q4	mkl	Shortterm Investments Availablefor Sale Accumulated Gross Unrealized Gain Before Tax ShorttermInvestmentsAvailableforSaleAccumulatedGrossUnrealizedGainBeforeTax	1355000	USD
CY2019Q4	mkl	Shortterm Investments Availablefor Sale Accumulated Gross Unrealized Loss Before Tax ShorttermInvestmentsAvailableforSaleAccumulatedGrossUnrealizedLossBeforeTax	60000	USD
CY2019Q4	mkl	Shortterm Investments Availablefor Sale ShorttermInvestmentsAvailableforSale	1196248000	USD
CY2019Q4	mkl	Investments Availablefor Sale Amortized Cost Basis InvestmentsAvailableforSaleAmortizedCostBasis	10643793000	USD
CY2019Q4	mkl	Investments Availablefor Sale Accumulated Gross Unrealized Gain Before Tax InvestmentsAvailableforSaleAccumulatedGrossUnrealizedGainBeforeTax	537843000	USD
CY2019Q4	mkl	Investments Availablefor Sale Accumulated Gross Unrealized Loss Before Tax InvestmentsAvailableforSaleAccumulatedGrossUnrealizedLossBeforeTax	14479000	USD
CY2019Q4	mkl	Investments Availablefor Sale InvestmentsAvailableforSale	11167157000	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	9950773000	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	223630000	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	131215000	USD
CY2018Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	10043188000	USD
CY2018Q4	mkl	Shortterm Investments Availablefor Sale Amortized Cost Basis ShorttermInvestmentsAvailableforSaleAmortizedCostBasis	1080027000	USD
CY2018Q4	mkl	Shortterm Investments Availablefor Sale Accumulated Gross Unrealized Gain Before Tax ShorttermInvestmentsAvailableforSaleAccumulatedGrossUnrealizedGainBeforeTax	443000	USD
CY2018Q4	mkl	Shortterm Investments Availablefor Sale Accumulated Gross Unrealized Loss Before Tax ShorttermInvestmentsAvailableforSaleAccumulatedGrossUnrealizedLossBeforeTax	2774000	USD
CY2018Q4	mkl	Shortterm Investments Availablefor Sale ShorttermInvestmentsAvailableforSale	1077696000	USD
CY2018Q4	mkl	Investments Availablefor Sale Amortized Cost Basis InvestmentsAvailableforSaleAmortizedCostBasis	11030800000	USD
CY2018Q4	mkl	Investments Availablefor Sale Accumulated Gross Unrealized Gain Before Tax InvestmentsAvailableforSaleAccumulatedGrossUnrealizedGainBeforeTax	224073000	USD
CY2018Q4	mkl	Investments Availablefor Sale Accumulated Gross Unrealized Loss Before Tax InvestmentsAvailableforSaleAccumulatedGrossUnrealizedLossBeforeTax	133989000	USD
CY2018Q4	mkl	Investments Availablefor Sale InvestmentsAvailableforSale	11120884000	USD
CY2019Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position Lessthan12 Months ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPositionLessthan12Months	3316000	USD
CY2019Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position Lessthan12 Months Accumulated Loss ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss	60000	USD
CY2019Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position12 Monthsor Longer ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPosition12MonthsorLonger	0	USD
CY2019Q4	mkl	Shortterm Investments Availableforsale Unrealized Loss Position Total ShorttermInvestmentsAvailableforsaleUnrealizedLossPositionTotal	3316000	USD
CY2019Q4	mkl	Shortterm Investments Availableforsale Unrealized Loss Position Accumulated Loss ShorttermInvestmentsAvailableforsaleUnrealizedLossPositionAccumulatedLoss	60000	USD
CY2019Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position12 Monthsor Longer Accumulated Loss ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss	0	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	7192000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	352025000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	611152000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	7287000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	963177000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	14479000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	201	securities
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	963200000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	14500000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	201	securities
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	122	securities
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	352000000.0	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	7300000	USD
CY2018Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position Lessthan12 Months ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPositionLessthan12Months	197643000	USD
CY2018Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position Lessthan12 Months Accumulated Loss ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss	2774000	USD
CY2018Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position12 Monthsor Longer ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPosition12MonthsorLonger	0	USD
CY2018Q4	mkl	Shortterm Investments Availableforsale Continuous Unrealized Loss Position12 Monthsor Longer Accumulated Loss ShorttermInvestmentsAvailableforsaleContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss	0	USD
CY2018Q4	mkl	Shortterm Investments Availableforsale Unrealized Loss Position Total ShorttermInvestmentsAvailableforsaleUnrealizedLossPositionTotal	197643000	USD
CY2018Q4	mkl	Shortterm Investments Availableforsale Unrealized Loss Position Accumulated Loss ShorttermInvestmentsAvailableforsaleUnrealizedLossPositionAccumulatedLoss	2774000	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	2610752000	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	56485000	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	1983912000	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	77504000	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	4594664000	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	133989000	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	1005	securities
CY2018Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	4600000000	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	134000000.0	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	1005	securities
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	541	securities
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	2000000000.0	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	77500000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	337917000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	333759000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	1256079000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	1289760000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	2157624000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	2274569000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	3068760000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	3355855000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	6820380000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate	7253943000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	9448840000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	9970909000	USD
CY2019	mkl	Estimated Average Duration Of Fixed Maturities EstimatedAverageDurationOfFixedMaturities	P5Y10M24D
CY2019	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	71351000	USD
CY2018	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	80016000	USD
CY2017	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	87768000	USD
CY2019	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	50425000	USD
CY2018	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	48765000	USD
CY2017	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	26772000	USD
CY2019	us-gaap	Investment Income Dividend InvestmentIncomeDividend	100222000	USD
CY2018	us-gaap	Investment Income Dividend InvestmentIncomeDividend	90840000	USD
CY2017	us-gaap	Investment Income Dividend InvestmentIncomeDividend	82096000	USD
CY2019	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	4368000	USD
CY2018	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-1924000	USD
CY2017	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	11076000	USD
CY2019	us-gaap	Other Interest And Dividend Income OtherInterestAndDividendIncome	5338000	USD
CY2018	us-gaap	Other Interest And Dividend Income OtherInterestAndDividendIncome	881000	USD
CY2017	us-gaap	Other Interest And Dividend Income OtherInterestAndDividendIncome	828000	USD
CY2019	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	467383000	USD
CY2018	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	450965000	USD
CY2017	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	422740000	USD
CY2019	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	15495000	USD
CY2018	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	16750000	USD
CY2017	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	17031000	USD
CY2019	us-gaap	Net Investment Income NetInvestmentIncome	451888000	USD
CY2018	us-gaap	Net Investment Income NetInvestmentIncome	434215000	USD
CY2017	us-gaap	Net Investment Income NetInvestmentIncome	405709000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	8708000	USD
CY2018	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	7106000	USD
CY2017	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	52282000	USD
CY2019	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2018	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2017	us-gaap	Impairment Of Investments ImpairmentOfInvestments	7589000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	10190000	USD
CY2018	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	19080000	USD
CY2017	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	12697000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-1482000	USD
CY2018	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-11974000	USD
CY2017	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	39585000	USD
CY2019	mkl	Changeinfairvalueofequitysecuritiessoldduringtheperiod Changeinfairvalueofequitysecuritiessoldduringtheperiod	38291000	USD
CY2018	mkl	Changeinfairvalueofequitysecuritiessoldduringtheperiod Changeinfairvalueofequitysecuritiessoldduringtheperiod	20177000	USD
CY2017	mkl	Changeinfairvalueofequitysecuritiessoldduringtheperiod Changeinfairvalueofequitysecuritiessoldduringtheperiod	6989000	USD
CY2019	mkl	Changein Fair Valueof Equity Securities Still Held ChangeinFairValueofEquitySecuritiesStillHeld	1564913000	USD
CY2018	mkl	Changein Fair Valueof Equity Securities Still Held ChangeinFairValueofEquitySecuritiesStillHeld	-445799000	USD
CY2017	mkl	Changein Fair Valueof Equity Securities Still Held ChangeinFairValueofEquitySecuritiesStillHeld	-51877000	USD
CY2019	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	1603204000	USD
CY2018	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	-425622000	USD
CY2017	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	-44888000	USD
CY2019	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1601722000	USD
CY2018	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	-437596000	USD
CY2017	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	-5303000	USD
CY2019	mkl	Other Comprehensive Income Securities Availablefor Sale Lifeand Annuity Benefits Reserves Adjustmentbefore Tax OtherComprehensiveIncomeSecuritiesAvailableforSaleLifeandAnnuityBenefitsReservesAdjustmentbeforeTax	-51390000	USD
CY2018	mkl	Other Comprehensive Income Securities Availablefor Sale Lifeand Annuity Benefits Reserves Adjustmentbefore Tax OtherComprehensiveIncomeSecuritiesAvailableforSaleLifeandAnnuityBenefitsReservesAdjustmentbeforeTax	0	USD
CY2017	mkl	Other Comprehensive Income Securities Availablefor Sale Lifeand Annuity Benefits Reserves Adjustmentbefore Tax OtherComprehensiveIncomeSecuritiesAvailableforSaleLifeandAnnuityBenefitsReservesAdjustmentbeforeTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	381890000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-299446000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	1125440000	USD
CY2019Q4	mkl	Restricted Investments Available For Sale RestrictedInvestmentsAvailableForSale	4134164000	USD
CY2018Q4	mkl	Restricted Investments Available For Sale RestrictedInvestmentsAvailableForSale	4781566000	USD
CY2019Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	427546000	USD
CY2018Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	382264000	USD
CY2019Q4	us-gaap	Restricted Cash And Investments RestrictedCashAndInvestments	4561710000	USD
CY2018Q4	us-gaap	Restricted Cash And Investments RestrictedCashAndInvestments	5163830000	USD
CY2019Q4	us-gaap	Restricted Cash And Investments RestrictedCashAndInvestments	4561710000	USD
CY2018Q4	us-gaap	Restricted Cash And Investments RestrictedCashAndInvestments	5163830000	USD
CY2019	mkl	Percentage Threshold Of Shareholders Equity Used To Define Concentration Of Investments PercentageThresholdOfShareholdersEquityUsedToDefineConcentrationOfInvestments	0.10
CY2019Q4	mkl	Ten Largest Equity Holdings TenLargestEquityHoldings	3000000000.0	USD
CY2019	mkl	Ten Largest Equity Holdings Percentage Of Equity Portfolio TenLargestEquityHoldingsPercentageOfEquityPortfolio	0.39
CY2019	mkl	Investments In Property And Casualty InvestmentsInPropertyAndCasualty	1200000000	USD
CY2019	mkl	Investments In Property And Casualty Percentage Of Equity Portfolio InvestmentsInPropertyAndCasualtyPercentageOfEquityPortfolio	0.16
CY2018Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	53728000	USD
CY2017Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	168809000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchases FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases	500000	USD
CY2018	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchases FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases	28900000	USD
CY2019Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	45992000	USD
CY2018Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	53728000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales	9448000	USD
CY2018	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales	35335000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	1212000	USD
CY2018	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	-108646000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
CY2018	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
CY2018	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
CY2019Q4	us-gaap	Premiums Receivable Gross PremiumsReceivableGross	1424881000	USD
CY2018Q4	us-gaap	Premiums Receivable Gross PremiumsReceivableGross	1327549000	USD
CY2019Q4	mkl	Trade Accounts Receivable Gross TradeAccountsReceivableGross	259062000	USD
CY2018Q4	mkl	Trade Accounts Receivable Gross TradeAccountsReceivableGross	226282000	USD
CY2019Q4	us-gaap	Other Receivables OtherReceivables	182582000	USD
CY2018Q4	us-gaap	Other Receivables OtherReceivables	154273000	USD
CY2019Q4	us-gaap	Accounts Receivable Gross AccountsReceivableGross	1866525000	USD
CY2018Q4	us-gaap	Accounts Receivable Gross AccountsReceivableGross	1708104000	USD
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	18723000	USD
CY2018Q4	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	15578000	USD
CY2019Q4	us-gaap	Premiums And Other Receivables Net PremiumsAndOtherReceivablesNet	1847802000	USD
CY2018Q4	us-gaap	Premiums And Other Receivables Net PremiumsAndOtherReceivablesNet	1692526000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	1777464000	USD
CY2018	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	548075000	USD
CY2018	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	91910000	USD
CY2018	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	4346000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	2237975000	USD
CY2019	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	118878000	USD
CY2019	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	-48305000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	2308548000	USD
CY2019Q4	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	139200000	USD
CY2019	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2018	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	91900000	USD
CY2017Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	1355681000	USD
CY2018	mkl	Intangible Assets Acquired During Period IntangibleAssetsAcquiredDuringPeriod	608345000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	115930000	USD
CY2018	us-gaap	Impairment Of Intangible Assets Excluding Goodwill ImpairmentOfIntangibleAssetsExcludingGoodwill	107288000	USD
CY2018	us-gaap	Finite Lived Intangible Assets Translation And Purchase Accounting Adjustments FiniteLivedIntangibleAssetsTranslationAndPurchaseAccountingAdjustments	-14612000	USD
CY2018Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	1726196000	USD
CY2019	mkl	Intangible Assets Acquired During Period IntangibleAssetsAcquiredDuringPeriod	113135000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	148638000	USD
CY2019	us-gaap	Finite Lived Intangible Assets Translation And Purchase Accounting Adjustments FiniteLivedIntangibleAssetsTranslationAndPurchaseAccountingAdjustments	47781000	USD
CY2019Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	1738474000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	150200000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	146300000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	142900000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	141000000.0	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	139100000	USD
CY2019Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	92400000	USD
CY2019	mkl	Intangible Assets Acquired During Period IntangibleAssetsAcquiredDuringPeriod	113100000	USD
CY2019	us-gaap	Acquired Finite Lived Intangible Assets Weighted Average Useful Life AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife	P11Y
CY2019Q4	us-gaap	Intangible Assets Gross Excluding Goodwill IntangibleAssetsGrossExcludingGoodwill	2358086000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	619612000	USD
CY2018Q4	us-gaap	Intangible Assets Gross Excluding Goodwill IntangibleAssetsGrossExcludingGoodwill	2196597000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	470401000	USD
CY2019	mkl	Lease Of Facilities And Furniture Maximum Duration LeaseOfFacilitiesAndFurnitureMaximumDuration	P15Y
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	62700000	USD
CY2018	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	52900000	USD
CY2017	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	44600000	USD
CY2019	mkl	Servicesandotherrevenues Servicesandotherrevenues	813202000	USD
CY2019	mkl	Productsexpenses Productsexpenses	1455245000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	232717000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	262139000	USD
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P8Y6M
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.033
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	49529000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	45463000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	39519000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	34095000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	26989000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	107410000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	303005000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	-40866000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	262139000	USD
CY2019	mkl	Number Of Reportable Ongoing Underwriting Segments NumberOfReportableOngoingUnderwritingSegments	2	segment
CY2019	us-gaap	Premiums Written Gross PremiumsWrittenGross	8779971000	USD
CY2019	us-gaap	Premiums Written Net PremiumsWrittenNet	5412071000	USD
CY2019	us-gaap	Premiums Earned Net PremiumsEarnedNet	5049793000	USD
CY2019	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	3426441000	USD
CY2019	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	-535251000	USD
CY2019	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1100496000	USD
CY2019	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	777597000	USD
CY2019	mkl	Underwriting Profit Loss UnderwritingProfitLoss	280510000	USD
CY2019	us-gaap	Net Investment Income NetInvestmentIncome	451888000	USD
CY2019	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	1601722000	USD
CY2019	mkl	Products Revenues ProductsRevenues	1609586000	USD
CY2019	mkl	Servicesandotherexpenses Servicesandotherexpenses	675679000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	148638000	USD
CY2019	mkl	Total Profit Loss TotalProfitLoss	2477346000	USD
CY2019	us-gaap	Interest Expense InterestExpense	171687000	USD
CY2019	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	-2265000	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-17586000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	2285808000	USD
CY2019	us-gaap	Combined Ratio CombinedRatio	0.94
CY2018	us-gaap	Premiums Written Gross PremiumsWrittenGross	7864469000	USD
CY2018	us-gaap	Premiums Written Net PremiumsWrittenNet	4787578000	USD
CY2018	us-gaap	Premiums Earned Net PremiumsEarnedNet	4712060000	USD
CY2018	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	3371699000	USD
CY2018	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	-550984000	USD
CY2018	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1009303000	USD
CY2018	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	768208000	USD
CY2018	mkl	Underwriting Profit Loss UnderwritingProfitLoss	113834000	USD
CY2018	us-gaap	Net Investment Income NetInvestmentIncome	434215000	USD
CY2018	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	-437596000	USD
CY2018	mkl	Products Revenues ProductsRevenues	1497523000	USD
CY2018	mkl	Servicesandotherrevenues Servicesandotherrevenues	635083000	USD
CY2018	mkl	Productsexpenses Productsexpenses	1413248000	USD
CY2018	mkl	Servicesandotherexpenses Servicesandotherexpenses	474924000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	115930000	USD
CY2018	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	199198000	USD
CY2018	mkl	Total Profit Loss TotalProfitLoss	39759000	USD
CY2018	us-gaap	Interest Expense InterestExpense	154212000	USD
CY2018	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	106598000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-7855000	USD
CY2018	us-gaap	Combined Ratio CombinedRatio	0.98
CY2017	us-gaap	Premiums Written Gross PremiumsWrittenGross	5506960000	USD
CY2017	us-gaap	Premiums Written Net PremiumsWrittenNet	4417787000	USD
CY2017	us-gaap	Premiums Earned Net PremiumsEarnedNet	4247978000	USD
CY2017	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	3367223000	USD
CY2017	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	-501462000	USD
CY2017	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	894353000	USD
CY2017	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	695111000	USD
CY2017	mkl	Underwriting Profit Loss UnderwritingProfitLoss	-207247000	USD
CY2017	us-gaap	Net Investment Income NetInvestmentIncome	405709000	USD
CY2017	mkl	Net Investment Gains Losses NetInvestmentGainsLosses	-5303000	USD
CY2017	mkl	Products Revenues ProductsRevenues	951012000	USD
CY2017	mkl	Servicesandotherrevenues Servicesandotherrevenues	462263000	USD
CY2017	mkl	Productsexpenses Productsexpenses	850449000	USD
CY2017	mkl	Servicesandotherexpenses Servicesandotherexpenses	458621000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	80758000	USD
CY2017	mkl	Total Profit Loss TotalProfitLoss	216606000	USD
CY2017	us-gaap	Interest Expense InterestExpense	132451000	USD
CY2017	us-gaap	Foreign Currency Transaction Gain Loss Realized ForeignCurrencyTransactionGainLossRealized	3140000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	87295000	USD
CY2017	us-gaap	Combined Ratio CombinedRatio	1.05
CY2019Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	566042000	USD
CY2019Q4	us-gaap	Unearned Premiums UnearnedPremiums	4057727000	USD
CY2019Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	14728676000	USD
CY2018Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	474513000	USD
CY2018Q4	us-gaap	Unearned Premiums UnearnedPremiums	3611028000	USD
CY2018Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	14276479000	USD
CY2019	us-gaap	Premiums Earned Net PremiumsEarnedNet	5049793000	USD
CY2018	us-gaap	Premiums Earned Net PremiumsEarnedNet	4712060000	USD
CY2017	us-gaap	Premiums Earned Net PremiumsEarnedNet	4247978000	USD
CY2019	us-gaap	Premiums Written Gross PremiumsWrittenGross	8779971000	USD
CY2018	us-gaap	Premiums Written Gross PremiumsWrittenGross	7864469000	USD
CY2017	us-gaap	Premiums Written Gross PremiumsWrittenGross	5506960000	USD
CY2019Q4	us-gaap	Assets Assets	37473815000	USD
CY2018Q4	us-gaap	Assets Assets	33306263000	USD
CY2017Q4	us-gaap	Assets Assets	32805016000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	2422788000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	2132606000	USD
CY2017	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1413275000	USD
CY2019	us-gaap	Schedule Of Liability For Unpaid Claims And Claims Adjustment Expense ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense	<span style="font-family:inherit;font-size:10pt;">The following table presents a reconciliation of consolidated beginning and ending reserves for losses and loss adjustment expenses.</span><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div><div style="line-height:120%;font-size:10pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;width:99.80506822612085%;border-collapse:collapse;text-align:left;"><tr><td colspan="12"/></tr><tr><td style="width:59%;"/><td style="width:1%;"/><td style="width:11%;"/><td style="width:1%;"/><td style="width:1%;"/><td style="width:1%;"/><td style="width:11%;"/><td style="width:1%;"/><td style="width:1%;"/><td style="width:1%;"/><td style="width:11%;"/><td style="width:1%;"/></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="11" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:center;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Years Ended December 31,</span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-style:italic;text-decoration:underline;">(dollars in thousands)</span></div></td><td colspan="3" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;">2019</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="3" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">2018</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="3" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">2017</span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Net reserves for losses and loss adjustment expenses, beginning of year</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;background-color:#cceeff;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;">$</span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>9,214,443</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;background-color:#cceeff;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">$</span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>8,964,945</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;background-color:#cceeff;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">$</span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>8,108,717</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:28px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Effect of foreign currency rate changes on beginning of year balance</span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>18,857</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>(69,119</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-right:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">)</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>110,079</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Adjusted net reserves for losses and loss adjustment expenses, beginning of year</span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>9,233,300</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>8,895,826</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>8,218,796</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Incurred losses and loss adjustment expenses:</span></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:28px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Current accident year</span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>3,426,441</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>3,371,699</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>3,367,223</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:28px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Prior accident years</span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>(535,307</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-right:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;">)</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>(551,040</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-right:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">)</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>(497,627</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-right:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">)</span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:28px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Total incurred losses and loss adjustment expenses</span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>2,891,134</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>2,820,659</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>2,869,596</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Payments:</span></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="3" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:28px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Current accident year</span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>671,208</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>666,515</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>671,112</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:28px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Prior accident years</span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>1,979,032</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>1,835,027</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>1,513,580</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:28px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Total payments</span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>2,650,240</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>2,501,542</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>2,184,692</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Effect of foreign currency rate changes on current year activity</span></div></td><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>1,067</span></span></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>(500</span></span></div></td><td style="vertical-align:bottom;padding-right:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">)</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>3,752</span></span></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Net reserves for losses and loss adjustment expenses of acquired insurance companies</span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>—</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>—</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>57,493</span></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Net reserves for losses and loss adjustment expenses, end of year</span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>9,475,261</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>9,214,443</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>8,964,945</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Reinsurance recoverables on unpaid losses</span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>5,253,415</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>5,062,036</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>4,619,336</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#cceeff;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Gross reserves for losses and loss adjustment expenses, end of year</span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;">$</span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;"><span>14,728,676</span></span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">$</span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>14,276,479</span></span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">$</span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><span>13,584,281</span></span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr></table></div><span style="font-family:inherit;font-size:10pt;"><br/></span></div><div style="line-height:120%;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div>
CY2018Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	9214443000	USD
CY2017Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	8964945000	USD
CY2016Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	8108717000	USD
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	18857000	USD
CY2018Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	-69119000	USD
CY2017Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	110079000	USD
CY2018Q4	mkl	Adjusted Liability For Unpaid Claims And Claims Adjustment Expense Net AdjustedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	9233300000	USD
CY2017Q4	mkl	Adjusted Liability For Unpaid Claims And Claims Adjustment Expense Net AdjustedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	8895826000	USD
CY2016Q4	mkl	Adjusted Liability For Unpaid Claims And Claims Adjustment Expense Net AdjustedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	8218796000	USD
CY2019	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	3426441000	USD
CY2018	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	3371699000	USD
CY2017	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	3367223000	USD
CY2019	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-535307000	USD
CY2018	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-551040000	USD
CY2017	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-497627000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	2891134000	USD
CY2018	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	2820659000	USD
CY2017	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	2869596000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	671208000	USD
CY2018	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	666515000	USD
CY2017	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	671112000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	1979032000	USD
CY2018	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	1835027000	USD
CY2017	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	1513580000	USD
CY2019	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	2650240000	USD
CY2018	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	2501542000	USD
CY2017	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	2184692000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Currency Translation Gain Loss LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCurrencyTranslationGainLoss	1067000	USD
CY2018	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Currency Translation Gain Loss LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCurrencyTranslationGainLoss	-500000	USD
CY2017	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Currency Translation Gain Loss LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCurrencyTranslationGainLoss	3752000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Business Acquisitions LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitions	0	USD
CY2018	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Business Acquisitions LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitions	0	USD
CY2017	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Business Acquisitions LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitions	57493000	USD
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	9475261000	USD
CY2018Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	9214443000	USD
CY2017Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	8964945000	USD
CY2019Q4	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	5253415000	USD
CY2018Q4	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	5062036000	USD
CY2017Q4	us-gaap	Reinsurance Receivables Incurred But Not Reported Claims ReinsuranceReceivablesIncurredButNotReportedClaims	4619336000	USD
CY2019Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	14728676000	USD
CY2018Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	14276479000	USD
CY2017Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	13584281000	USD
CY2019	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-535300000	USD
CY2018	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-551000000.0	USD
CY2017	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-497600000	USD
CY2017	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Business Acquisitions LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitions	57500000	USD
CY2017	mkl	Prior Year Development Completionof Part Vii Transfer PriorYearDevelopmentCompletionofPartVIITransfer	-3900000	USD
CY2019Q4	mkl	Ibnr Reserves Percentage Of Total Unpaid Losses And Loss Adjustment Expenses IBNRReservesPercentageOfTotalUnpaidLossesAndLossAdjustmentExpenses	0.65
CY2018Q4	mkl	Ibnr Reserves Percentage Of Total Unpaid Losses And Loss Adjustment Expenses IBNRReservesPercentageOfTotalUnpaidLossesAndLossAdjustmentExpenses	0.64
CY2019Q4	us-gaap	Shortduration Insurance Contracts Liability For Unpaid Claims And Allocated Claim Adjustment Expense Net ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet	9253056000	USD
CY2019Q4	us-gaap	Reinsurance Recoverable For Unpaid Claims And Claims Adjustments ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments	5253415000	USD
CY2019Q4	us-gaap	Shortduration Insurance Contracts Liability For Unpaid Claims And Claims Adjustment Expense Accumulated Unallocated Claim Adjustment Expense ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAccumulatedUnallocatedClaimAdjustmentExpense	264029000	USD
CY2019Q4	mkl	Unpaid Losses And Loss Adjustment Expenses Unamortized Fair Value Adjustment UnpaidLossesAndLossAdjustmentExpensesUnamortizedFairValueAdjustment	-41824000	USD
CY2017	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	1287395000	USD
CY2018	us-gaap	Premiums Earned Net PremiumsEarnedNet	4712060000	USD
CY2017	us-gaap	Direct Premiums Written DirectPremiumsWritten	4172467000	USD
CY2017	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	1334493000	USD
CY2017	us-gaap	Ceded Premiums Written CededPremiumsWritten	1089173000	USD
CY2017	us-gaap	Premiums Written Net PremiumsWrittenNet	4417787000	USD
CY2017	us-gaap	Direct Premiums Earned DirectPremiumsEarned	4068622000	USD
CY2019Q4	us-gaap	Shortduration Insurance Contracts Liability For Unpaid Claims And Claim Adjustment Expense Aggregate Reconciling Items ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimAdjustmentExpenseAggregateReconcilingItems	222205000	USD
CY2019Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	14728676000	USD
CY2019	us-gaap	Direct Premiums Written DirectPremiumsWritten	7341388000	USD
CY2019	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	1438583000	USD
CY2019	us-gaap	Ceded Premiums Written CededPremiumsWritten	3367900000	USD
CY2019	us-gaap	Premiums Written Net PremiumsWrittenNet	5412071000	USD
CY2019	us-gaap	Direct Premiums Earned DirectPremiumsEarned	6962507000	USD
CY2019	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	1368153000	USD
CY2019	us-gaap	Ceded Premiums Earned CededPremiumsEarned	3280867000	USD
CY2019	us-gaap	Premiums Earned Net PremiumsEarnedNet	5049793000	USD
CY2018	us-gaap	Direct Premiums Written DirectPremiumsWritten	6584804000	USD
CY2018	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	1279665000	USD
CY2018	us-gaap	Ceded Premiums Written CededPremiumsWritten	3076891000	USD
CY2018	us-gaap	Premiums Written Net PremiumsWrittenNet	4787578000	USD
CY2018	us-gaap	Direct Premiums Earned DirectPremiumsEarned	6235218000	USD
CY2018	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	1319613000	USD
CY2018	us-gaap	Ceded Premiums Earned CededPremiumsEarned	2842771000	USD
CY2017	us-gaap	Ceded Premiums Earned CededPremiumsEarned	1108039000	USD
CY2017	us-gaap	Premiums Earned Net PremiumsEarnedNet	4247978000	USD
CY2019	mkl	Premiums Percentage Ceded To Gross PremiumsPercentageCededToGross	0.39
CY2018	mkl	Premiums Percentage Ceded To Gross PremiumsPercentageCededToGross	0.38
CY2017	mkl	Premiums Percentage Ceded To Gross PremiumsPercentageCededToGross	0.21
CY2019	us-gaap	Premiums Percentage Assumed To Net PremiumsPercentageAssumedToNet	0.27
CY2018	us-gaap	Premiums Percentage Assumed To Net PremiumsPercentageAssumedToNet	0.28
CY2017	us-gaap	Premiums Percentage Assumed To Net PremiumsPercentageAssumedToNet	0.30
CY2019Q4	mkl	Annuities Subject To Discretionary Withdrawal AnnuitiesSubjectToDiscretionaryWithdrawal	0	USD
CY2019Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	985729000	USD
CY2018Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	1001453000	USD
CY2019	mkl	Adjustmentto Lifeand Annuity Benefits AdjustmenttoLifeandAnnuityBenefits	51400000	USD
CY2019Q4	mkl	Cumulative Adjustment Lifeand Annuity Benefits CumulativeAdjustmentLifeandAnnuityBenefits	51400000	USD
CY2018	mkl	Adjustmentto Lifeand Annuity Benefits AdjustmenttoLifeandAnnuityBenefits	0	USD
CY2019Q4	mkl	Traditional Life Interest Rate Average TraditionalLifeInterestRateAverage	0.023
CY2019Q4	mkl	Life And Annuity Benefits Reserve Single Contract Concentration LifeAndAnnuityBenefitsReserveSingleContractConcentration	0.328
CY2019Q4	us-gaap	Liability For Future Policy Benefits Life LiabilityForFuturePolicyBenefitsLife	125094000	USD
CY2018Q4	us-gaap	Liability For Future Policy Benefits Life LiabilityForFuturePolicyBenefitsLife	122798000	USD
CY2019Q4	us-gaap	Liability For Future Policy Benefits Individual And Group Annuities And Supplementary Contracts LiabilityForFuturePolicyBenefitsIndividualAndGroupAnnuitiesAndSupplementaryContracts	813476000	USD
CY2018Q4	us-gaap	Liability For Future Policy Benefits Individual And Group Annuities And Supplementary Contracts LiabilityForFuturePolicyBenefitsIndividualAndGroupAnnuitiesAndSupplementaryContracts	827773000	USD
CY2019Q4	us-gaap	Liability For Future Policy Benefits Disability And Accident Benefits LiabilityForFuturePolicyBenefitsDisabilityAndAccidentBenefits	47159000	USD
CY2018Q4	us-gaap	Liability For Future Policy Benefits Disability And Accident Benefits LiabilityForFuturePolicyBenefitsDisabilityAndAccidentBenefits	50882000	USD
CY2019Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	3534183000	USD
CY2018Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	3009577000	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-17600000	USD
CY2019Q4	us-gaap	Debt Instrument Fair Value DebtInstrumentFairValue	3900000000	USD
CY2018Q4	us-gaap	Debt Instrument Fair Value DebtInstrumentFairValue	3000000000.0	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	63519000	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	25546000	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	356185000	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	250428000	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	0	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	2879852000	USD
CY2019Q4	mkl	Long Term Debt Maturities Total Future Repayments Of Principal LongTermDebtMaturitiesTotalFutureRepaymentsOfPrincipal	3575530000	USD
CY2019Q4	us-gaap	Debt Instrument Unamortized Discount Premium Net DebtInstrumentUnamortizedDiscountPremiumNet	35673000	USD
CY2019Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	5674000	USD
CY2019Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	3534183000	USD
CY2019	us-gaap	Interest Paid InterestPaid	169700000	USD
CY2018	us-gaap	Interest Paid InterestPaid	155400000	USD
CY2017	us-gaap	Interest Paid InterestPaid	141300000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1664762000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	99373000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	337704000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	621046000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	-107228000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	-250409000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	2285808000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-7855000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	87295000	USD
CY2019	mkl	Current Domestic Income Tax Expense Benefit CurrentDomesticIncomeTaxExpenseBenefit	139597000	USD
CY2018	mkl	Current Domestic Income Tax Expense Benefit CurrentDomesticIncomeTaxExpenseBenefit	77936000	USD
CY2017	mkl	Current Domestic Income Tax Expense Benefit CurrentDomesticIncomeTaxExpenseBenefit	-19255000	USD
CY2019	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	23364000	USD
CY2018	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	41833000	USD
CY2017	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	29882000	USD
CY2018	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	4951000	USD
CY2017	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	37207000	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	18430000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	162961000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	119769000	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	10627000	USD
CY2019	mkl	Deferred Domestic Income Tax Expense Benefit DeferredDomesticIncomeTaxExpenseBenefit	217928000	USD
CY2018	mkl	Deferred Domestic Income Tax Expense Benefit DeferredDomesticIncomeTaxExpenseBenefit	-77255000	USD
CY2017	mkl	Deferred Domestic Income Tax Expense Benefit DeferredDomesticIncomeTaxExpenseBenefit	-222427000	USD
CY2019	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	105457000	USD
CY2018	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	79984000	USD
CY2017	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	-101663000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	323385000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	2729000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-324090000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	486346000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	122498000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-313463000	USD
CY2019	us-gaap	Income Taxes Paid IncomeTaxesPaid	128200000	USD
CY2018	us-gaap	Income Taxes Paid IncomeTaxesPaid	63100000	USD
CY2017	us-gaap	Income Taxes Paid IncomeTaxesPaid	70200000	USD
CY2019Q4	us-gaap	Accrued Income Taxes AccruedIncomeTaxes	64100000	USD
CY2018Q4	us-gaap	Accrued Income Taxes AccruedIncomeTaxes	83700000	USD
CY2019Q4	us-gaap	Income Tax Receivable IncomeTaxReceivable	6300000	USD
CY2018Q4	us-gaap	Income Tax Receivable IncomeTaxReceivable	49300000	USD
CY2017	us-gaap	Tax Cuts And Jobs Act Of2017 Change In Tax Rate Income Tax Expense Benefit TaxCutsAndJobsActOf2017ChangeInTaxRateIncomeTaxExpenseBenefit	-339900000	USD
CY2018	us-gaap	Tax Cuts And Jobs Act Of2017 Change In Tax Rate Income Tax Expense Benefit TaxCutsAndJobsActOf2017ChangeInTaxRateIncomeTaxExpenseBenefit	-5700000	USD
CY2018	mkl	Changein Tax Statusof Uk Subsidiaries Onetime Tax Expense ChangeinTaxStatusofUKSubsidiariesOnetimeTaxExpense	-103300000	USD
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	480020000	USD
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	-1650000	USD
CY2017	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	30553000	USD
CY2019	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	14718000	USD
CY2018	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	18927000	USD
CY2017	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	41565000	USD
CY2019	mkl	Changein Tax Statusof Uk Subsidiaries Onetime Tax Expense ChangeinTaxStatusofUKSubsidiariesOnetimeTaxExpense	6658000	USD
CY2018	mkl	Changein Tax Statusof Uk Subsidiaries Onetime Tax Expense ChangeinTaxStatusofUKSubsidiariesOnetimeTaxExpense	-103281000	USD
CY2017	mkl	Changein Tax Statusof Uk Subsidiaries Onetime Tax Expense ChangeinTaxStatusofUKSubsidiariesOnetimeTaxExpense	0	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	4104000	USD
CY2018	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	3617000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	39429000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	46662000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Other DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsOther	35132000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Other DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsOther	30308000	USD
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$MKL
MARKEL GROUP INC. Stock $mkl

2019 Q4 Form 10-K Financial Statement

#000109634320000039 Filed on February 21, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$MKL MARKEL GROUP INC. Stock $mkl

2019 Q4 Form 10-K Financial Statement

#000109634320000039 Filed on February 21, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$MKL
MARKEL GROUP INC. Stock $mkl