$WTM
WHITE MOUNTAINS INSURANCE GROUP LTD Stock $wtm

$wtm Overview Financials Valuation SEC Filings Company Website

2023 Q1 Form 10-K Financial Statement

#000077686723000004 Filed on February 27, 2023

Income Statement

Concept	2023 Q1	2022 Q4	2022 Q3
Revenue	$531.9M	$437.6M	$383.2M
YoY Change	52.45%	25.03%	-3894.06%
Cost Of Revenue	$13.90M		$25.00M
YoY Change	-35.05%		4.17%
Gross Profit	$518.0M		$358.2M
YoY Change	58.17%		-1150.44%
Gross Profit Margin	97.39%		93.48%
Selling, General & Admin	$109.9M	$147.6M	$112.1M
YoY Change	18.94%	-11.99%	-22.8%
% of Gross Profit	21.22%		31.3%
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	-$82.20M	$20.40M	$38.60M
YoY Change	-613.75%	-47.56%	-31.32%
% of Gross Profit	-15.87%		10.78%
Operating Expenses	$320.2M	$295.8M	$403.7M
YoY Change	19.34%	-2.05%	18.08%
Operating Profit	$197.8M		-$45.50M
YoY Change	234.12%		-87.9%
Interest Expense	-$12.60M	-$12.80M	-$10.50M
YoY Change	82.61%	13.27%	1.94%
% of Operating Profit	-6.37%
Other Income/Expense, Net
YoY Change
Pretax Income	$199.1M	$129.0M	-$31.00M
YoY Change	-1731.97%	251.5%	-91.44%
Income Tax	$11.90M	$67.50M	-$7.400M
% Of Pretax Income	5.98%	52.33%
Net Earnings	$179.5M	$243.6M	$888.2M
YoY Change	437.43%	642.68%	-339.15%
Net Earnings / Revenue	33.75%	55.67%	231.78%
Basic Earnings Per Share	$69.83		$306.90
Diluted Earnings Per Share	$69.83	$96.16	$306.90
COMMON SHARES
Basic Shares Outstanding	2.568M shares	2.576M shares	2.907M shares
Diluted Shares Outstanding	2.539M shares		2.856M shares

Balance Sheet

Concept	2023 Q1	2022 Q4	2022 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$202.7M	$255.0M	$245.7M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment		$25.20M	$24.50M
YoY Change		-40.28%	9.38%
Goodwill	$168.8M	$176.5M	$175.5M
YoY Change	-73.68%	24.03%	-73.86%
Intangibles	$207.4M	$215.9M	$217.7M
YoY Change		8.93%
Long-Term Investments	$5.435B	$5.170B	$5.154B
YoY Change	31.4%	21.21%	22.61%
Other Assets			$0.00
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$7.959B	$7.389B	$7.545B
YoY Change	8.19%	5.55%	6.06%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$52.10M	$141.2M	$115.3M
YoY Change	-35.92%	19.26%	75.49%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$52.10M	$141.2M	$115.3M
YoY Change	-35.92%	19.26%	75.49%
LONG-TERM LIABILITIES
Long-Term Debt	$556.3M	$575.2M	$615.5M
YoY Change	-19.48%	-17.0%	-13.36%
Other Long-Term Liabilities	$296.0M	$268.8M	$237.8M
YoY Change	9.51%	0.41%	-26.79%
Total Long-Term Liabilities	$852.3M	$844.0M	$853.3M
YoY Change	-11.33%	-12.15%	-17.57%
TOTAL LIABILITIES
Total Short-Term Liabilities	$52.10M	$141.2M	$115.3M
Total Long-Term Liabilities	$852.3M	$844.0M	$853.3M
Total Liabilities	$3.866B	$3.454B	$3.679B
YoY Change	4.85%	4.8%	6.34%
SHAREHOLDERS EQUITY
Retained Earnings	$3.367B	$3.212B	$3.176B
YoY Change	13.91%	8.6%	8.2%
Common Stock	$2.600M	$538.6M	$2.600M
YoY Change	-13.33%	-8.54%	-13.33%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$3.902B	$3.747B	$3.708B
YoY Change
Total Liabilities & Shareholders Equity	$7.959B	$7.389B	$7.545B
YoY Change	8.19%	5.55%	6.06%

Cashflow Statement

Concept	2023 Q1	2022 Q4	2022 Q3
OPERATING ACTIVITIES
Net Income	$179.5M	$243.6M	$888.2M
YoY Change	437.43%	642.68%	-339.15%
Depreciation, Depletion And Amortization	-$82.20M	$20.40M	$38.60M
YoY Change	-613.75%	-47.56%	-31.32%
Cash From Operating Activities	$85.60M	$208.1M	$115.6M
YoY Change	-306.27%	-2912.16%	90.44%
INVESTING ACTIVITIES
Capital Expenditures
YoY Change
Acquisitions	$0.00
YoY Change
Other Investing Activities	$11.20M	-$152.0M	$234.3M
YoY Change	-354.55%	290.75%	-190.22%
Cash From Investing Activities	-$96.60M	-$152.0M	$234.3M
YoY Change	-169.1%	290.75%	-190.22%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net	$20.00M
YoY Change
Cash From Financing Activities	-$41.30M	-46.80M	-487.6M
YoY Change	32.8%	895.74%	-331.53%
NET CHANGE
Cash From Operating Activities	$85.60M	208.1M	115.6M
Cash From Investing Activities	-$96.60M	-152.0M	234.3M
Cash From Financing Activities	-$41.30M	-46.80M	-487.6M
Net Change In Cash	-$52.30M	9.300M	-137.7M
YoY Change	-177.14%	-118.24%	-1287.07%
FREE CASH FLOW
Cash From Operating Activities	$85.60M	$208.1M	$115.6M
Capital Expenditures
Free Cash Flow
YoY Change

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
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CY2022	dei	Document Period End Date DocumentPeriodEndDate	2022-12-31
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CY2022	dei	Entity File Number EntityFileNumber	1-8993
CY2022	dei	Entity Registrant Name EntityRegistrantName	WHITE MOUNTAINS INSURANCE GROUP, LTD.
CY2022	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	D0
CY2022	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	94-2708455
CY2022	dei	Entity Address Address Line1 EntityAddressAddressLine1	23 South Main Street, Suite 3B
CY2022	dei	Entity Address City Or Town EntityAddressCityOrTown	Hanover,
CY2022	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	03755-2053
CY2022	dei	Entity Address State Or Province EntityAddressStateOrProvince	NH
CY2022	dei	City Area Code CityAreaCode	603
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CY2021	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	198600000	usd
CY2020	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	39100000	usd
CY2022	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	21900000	usd
CY2021	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	41800000	usd
CY2020	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	5800000	usd
CY2022	us-gaap	Increase Decrease In Funds Held Under Reinsurance Agreements IncreaseDecreaseInFundsHeldUnderReinsuranceAgreements	173000000.0	usd
CY2021	us-gaap	Increase Decrease In Funds Held Under Reinsurance Agreements IncreaseDecreaseInFundsHeldUnderReinsuranceAgreements	104200000	usd
CY2020	us-gaap	Increase Decrease In Funds Held Under Reinsurance Agreements IncreaseDecreaseInFundsHeldUnderReinsuranceAgreements	0	usd
CY2022	wtm	Increase Decrease In Restricted Cash Operating Activities IncreaseDecreaseInRestrictedCashOperatingActivities	-7700000	usd
CY2021	wtm	Increase Decrease In Restricted Cash Operating Activities IncreaseDecreaseInRestrictedCashOperatingActivities	-4500000	usd
CY2020	wtm	Increase Decrease In Restricted Cash Operating Activities IncreaseDecreaseInRestrictedCashOperatingActivities	0	usd
CY2022	wtm	Increase In Debt Securities Trading And Equity Securities Fvni IncreaseInDebtSecuritiesTradingAndEquitySecuritiesFVNI	137500000	usd
CY2021	wtm	Increase In Debt Securities Trading And Equity Securities Fvni IncreaseInDebtSecuritiesTradingAndEquitySecuritiesFVNI	44400000	usd
CY2020	wtm	Increase In Debt Securities Trading And Equity Securities Fvni IncreaseInDebtSecuritiesTradingAndEquitySecuritiesFVNI	0	usd
CY2022	wtm	Decrease In Debt Securities Trading And Equity Securities Fvni DecreaseInDebtSecuritiesTradingAndEquitySecuritiesFVNI	99800000	usd
CY2021	wtm	Decrease In Debt Securities Trading And Equity Securities Fvni DecreaseInDebtSecuritiesTradingAndEquitySecuritiesFVNI	223400000	usd
CY2020	wtm	Decrease In Debt Securities Trading And Equity Securities Fvni DecreaseInDebtSecuritiesTradingAndEquitySecuritiesFVNI	118300000	usd
CY2022	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-90400000	usd
CY2021	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-11700000	usd
CY2020	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-34800000	usd
CY2022	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	326300000	usd
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	-3700000	usd
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	-96100000	usd
CY2022	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	38700000	usd
CY2021	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	42300000	usd
CY2020	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	35500000	usd
CY2022	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	365000000.0	usd
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	38600000	usd
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	-60600000	usd
CY2022	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	455100000	usd
CY2021	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	-59800000	usd
CY2020	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	-60900000	usd
CY2022	wtm	Proceeds From Sale Of Trading Fixed Maturity And Convertible Fixed Maturity Investments ProceedsFromSaleOfTradingFixedMaturityAndConvertibleFixedMaturityInvestments	188700000	usd
CY2021	wtm	Proceeds From Sale Of Trading Fixed Maturity And Convertible Fixed Maturity Investments ProceedsFromSaleOfTradingFixedMaturityAndConvertibleFixedMaturityInvestments	286300000	usd
CY2020	wtm	Proceeds From Sale Of Trading Fixed Maturity And Convertible Fixed Maturity Investments ProceedsFromSaleOfTradingFixedMaturityAndConvertibleFixedMaturityInvestments	390000000.0	usd
CY2022	wtm	Proceeds From Maturities Of Trading Fixed Maturity And Convertible Fixed Maturity Investments ProceedsFromMaturitiesOfTradingFixedMaturityAndConvertibleFixedMaturityInvestments	198500000	usd
CY2021	wtm	Proceeds From Maturities Of Trading Fixed Maturity And Convertible Fixed Maturity Investments ProceedsFromMaturitiesOfTradingFixedMaturityAndConvertibleFixedMaturityInvestments	199000000.0	usd
CY2020	wtm	Proceeds From Maturities Of Trading Fixed Maturity And Convertible Fixed Maturity Investments ProceedsFromMaturitiesOfTradingFixedMaturityAndConvertibleFixedMaturityInvestments	180400000	usd
CY2022	wtm	Proceeds From Sale Of Trading Common Equity Securities ProceedsFromSaleOfTradingCommonEquitySecurities	0	usd
CY2021	wtm	Proceeds From Sale Of Trading Common Equity Securities ProceedsFromSaleOfTradingCommonEquitySecurities	176800000	usd
CY2020	wtm	Proceeds From Sale Of Trading Common Equity Securities ProceedsFromSaleOfTradingCommonEquitySecurities	787900000	usd
CY2022	us-gaap	Proceeds From Sale And Maturity Of Other Investments ProceedsFromSaleAndMaturityOfOtherInvestments	115400000	usd
CY2021	us-gaap	Proceeds From Sale And Maturity Of Other Investments ProceedsFromSaleAndMaturityOfOtherInvestments	106400000	usd
CY2020	us-gaap	Proceeds From Sale And Maturity Of Other Investments ProceedsFromSaleAndMaturityOfOtherInvestments	69900000	usd
CY2022	wtm	Proceeds From Payments For Release Of Cash Placed In Escrow ProceedsFromPaymentsForReleaseOfCashPlacedInEscrow	0	usd
CY2021	wtm	Proceeds From Payments For Release Of Cash Placed In Escrow ProceedsFromPaymentsForReleaseOfCashPlacedInEscrow	646300000	usd
CY2020	wtm	Proceeds From Payments For Release Of Cash Placed In Escrow ProceedsFromPaymentsForReleaseOfCashPlacedInEscrow	-646300000	usd
CY2022	wtm	Cash Payments For Pre Funding CashPaymentsForPreFunding	70000000.0	usd
CY2021	wtm	Cash Payments For Pre Funding CashPaymentsForPreFunding	0	usd
CY2020	wtm	Cash Payments For Pre Funding CashPaymentsForPreFunding	0	usd
CY2022	wtm	Payments To Acquire Trading Fixed Maturity And Convertible Fixed Maturity Investments PaymentsToAcquireTradingFixedMaturityAndConvertibleFixedMaturityInvestments	585500000	usd
CY2021	wtm	Payments To Acquire Trading Fixed Maturity And Convertible Fixed Maturity Investments PaymentsToAcquireTradingFixedMaturityAndConvertibleFixedMaturityInvestments	1219400000	usd
CY2020	wtm	Payments To Acquire Trading Fixed Maturity And Convertible Fixed Maturity Investments PaymentsToAcquireTradingFixedMaturityAndConvertibleFixedMaturityInvestments	537700000	usd
CY2022	wtm	Payments To Acquire Trading Common Equity Securities PaymentsToAcquireTradingCommonEquitySecurities	424500000	usd
CY2021	wtm	Payments To Acquire Trading Common Equity Securities PaymentsToAcquireTradingCommonEquitySecurities	203400000	usd
CY2020	wtm	Payments To Acquire Trading Common Equity Securities PaymentsToAcquireTradingCommonEquitySecurities	33800000	usd
CY2022	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	178800000	usd
CY2021	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	218000000.0	usd
CY2020	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	76800000	usd
CY2022	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	300000	usd
CY2021	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	52200000	usd
CY2020	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	1500000	usd
CY2022	us-gaap	Payments For Proceeds From Businesses And Interest In Affiliates PaymentsForProceedsFromBusinessesAndInterestInAffiliates	67900000	usd
CY2021	us-gaap	Payments For Proceeds From Businesses And Interest In Affiliates PaymentsForProceedsFromBusinessesAndInterestInAffiliates	-10600000	usd
CY2020	us-gaap	Payments For Proceeds From Businesses And Interest In Affiliates PaymentsForProceedsFromBusinessesAndInterestInAffiliates	9100000	usd
CY2022	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	4400000	usd
CY2021	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-3800000	usd
CY2020	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-4100000	usd
CY2022	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	108400000	usd
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-151800000	usd
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	189500000	usd
CY2022	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	7100000	usd
CY2021	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	-56500000	usd
CY2020	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	-124900000	usd
CY2022	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	115500000	usd
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-208300000	usd
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	64600000	usd
CY2022	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	213800000	usd
CY2021	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	401700000	usd
CY2020	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	32200000	usd
CY2022	us-gaap	Repayments Of Debt RepaymentsOfDebt	56700000	usd
CY2021	us-gaap	Repayments Of Debt RepaymentsOfDebt	120100000	usd
CY2020	us-gaap	Repayments Of Debt RepaymentsOfDebt	1900000	usd
CY2022	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	3000000.0	usd
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	3100000	usd
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	3200000	usd
CY2022	wtm	Issuances Of Subsidiary Shares To Non Controlling Interest Shareholders IssuancesOfSubsidiarySharesToNonControllingInterestShareholders	-74600000	usd
CY2021	wtm	Issuances Of Subsidiary Shares To Non Controlling Interest Shareholders IssuancesOfSubsidiarySharesToNonControllingInterestShareholders	-6500000	usd
CY2020	wtm	Issuances Of Subsidiary Shares To Non Controlling Interest Shareholders IssuancesOfSubsidiarySharesToNonControllingInterestShareholders	0	usd
CY2022	wtm	Net Distributions From Contributions To Discontinued Operations NetDistributionsFromContributionsToDiscontinuedOperations	11600000	usd
CY2021	wtm	Net Distributions From Contributions To Discontinued Operations NetDistributionsFromContributionsToDiscontinuedOperations	0	usd
CY2020	wtm	Net Distributions From Contributions To Discontinued Operations NetDistributionsFromContributionsToDiscontinuedOperations	-85000000.0	usd
CY2022	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	615800000	usd
CY2021	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	107500000	usd
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	85200000	usd
CY2022	wtm	Members Capital Contribution MembersCapitalContribution	81400000	usd
CY2021	wtm	Members Capital Contribution MembersCapitalContribution	62200000	usd
CY2020	wtm	Members Capital Contribution MembersCapitalContribution	68900000	usd
CY2022	us-gaap	Proceeds From Payments To Minority Shareholders ProceedsFromPaymentsToMinorityShareholders	-21600000	usd
CY2021	us-gaap	Proceeds From Payments To Minority Shareholders ProceedsFromPaymentsToMinorityShareholders	700000	usd
CY2020	us-gaap	Proceeds From Payments To Minority Shareholders ProceedsFromPaymentsToMinorityShareholders	-2500000	usd
CY2022	wtm	Fidus Re Premium Payment FidusRePremiumPayment	10100000	usd
CY2021	wtm	Fidus Re Premium Payment FidusRePremiumPayment	8800000	usd
CY2020	wtm	Fidus Re Premium Payment FidusRePremiumPayment	3000000.0	usd
CY2022	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-1600000	usd
CY2021	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-13000000.0	usd
CY2020	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-100000	usd
CY2022	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	-327400000	usd
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	218600000	usd
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	-79800000	usd
CY2022	us-gaap	Cash Provided By Used In Financing Activities Discontinued Operations CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations	-17500000	usd
CY2021	us-gaap	Cash Provided By Used In Financing Activities Discontinued Operations CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations	-1000000.0	usd
CY2020	us-gaap	Cash Provided By Used In Financing Activities Discontinued Operations CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations	128800000	usd
CY2022	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-344900000	usd
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	217600000	usd
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	49000000.0	usd
CY2022	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	107300000	usd
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	63100000	usd
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	13600000	usd
CY2021Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	4500000	usd
CY2020Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	0.0	usd
CY2019Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	0.0	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	147700000	usd
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	84600000	usd
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	71000000.0	usd
CY2022Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	12200000	usd
CY2021Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	4500000	usd
CY2020Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	0.0	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	255000000.0	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	147700000	usd
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	84600000	usd
CY2022	us-gaap	Use Of Estimates UseOfEstimates	<div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Use of Estimates</span></div><div style="text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.</span></div>
CY2022	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	3	segment
CY2022	wtm	Percentage Of Investments Recorded At Fair Value PercentageOfInvestmentsRecordedAtFairValue	0.72
CY2022	wtm	Fair Value Measurements Variance Thresholdfor Outliers FairValueMeasurementsVarianceThresholdforOutliers	500000	usd
CY2022	wtm	Fair Value Measurements Variance Thresholdfor Outliers Percent FairValueMeasurementsVarianceThresholdforOutliersPercent	0.05
CY2022	us-gaap	Derivatives Reporting Of Derivative Activity DerivativesReportingOfDerivativeActivity	<div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Derivatives </span></div><div style="text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">From time to time, White Mountains holds derivative financial instruments for risk management purposes. White Mountains recognizes all derivatives as either assets or liabilities, measured at fair value, on its consolidated balance sheet. Changes in the fair value of derivative instruments that meet the criteria for hedge accounting are recognized in other comprehensive income (loss) and reclassified into current period pre-tax income (loss) when the hedged items are recognized therein. Changes in the fair value of derivative instruments that do not meet the criteria for hedge accounting are recognized in current period pre-tax income (loss).</span></div><div style="text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">As of December 31, 2022, White Mountains holds an interest rate cap derivative instrument that does not meet the criteria for hedge accounting. See </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Note 9 — “Derivatives”</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">.</span></div>
CY2022Q4	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-3500000	usd
CY2021Q4	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	5100000	usd
CY2022	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	126500000	usd
CY2021	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	84800000	usd
CY2020	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	132200000	usd
CY2022	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	2100000	usd
CY2021	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	2300000	usd
CY2020	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	1200000	usd
CY2022	us-gaap	Net Investment Income NetInvestmentIncome	124400000	usd
CY2021	us-gaap	Net Investment Income NetInvestmentIncome	82500000	usd
CY2020	us-gaap	Net Investment Income NetInvestmentIncome	131000000.0	usd
CY2022	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	115100000	usd
CY2021	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	156800000	usd
CY2020	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	187100000	usd
CY2022	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	-313400000	usd
CY2021	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	-395200000	usd
CY2020	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	529700000	usd
CY2022	wtm	Gain Loss On Investments Exchange Rate Effect GainLossOnInvestmentsExchangeRateEffect	-29300000	usd
CY2021	wtm	Gain Loss On Investments Exchange Rate Effect GainLossOnInvestmentsExchangeRateEffect	-7700000	usd
CY2020	wtm	Gain Loss On Investments Exchange Rate Effect GainLossOnInvestmentsExchangeRateEffect	4000000.0	usd
CY2022	us-gaap	Debt Securities Trading Realized Gain DebtSecuritiesTradingRealizedGain	129900000	usd
CY2021	us-gaap	Debt Securities Trading Realized Gain DebtSecuritiesTradingRealizedGain	212300000	usd
CY2020	us-gaap	Debt Securities Trading Realized Gain DebtSecuritiesTradingRealizedGain	214400000	usd
CY2022	us-gaap	Debt Securities Trading Realized Loss DebtSecuritiesTradingRealizedLoss	14800000	usd
CY2021	us-gaap	Debt Securities Trading Realized Loss DebtSecuritiesTradingRealizedLoss	55500000	usd
CY2020	us-gaap	Debt Securities Trading Realized Loss DebtSecuritiesTradingRealizedLoss	27300000	usd
CY2022	us-gaap	Proceeds From Sale Maturity And Collection Of Longterm Investments ProceedsFromSaleMaturityAndCollectionOfLongtermInvestments	500000000	usd
CY2021	us-gaap	Proceeds From Sale Maturity And Collection Of Longterm Investments ProceedsFromSaleMaturityAndCollectionOfLongtermInvestments	800000000	usd
CY2020	us-gaap	Proceeds From Sale Maturity And Collection Of Longterm Investments ProceedsFromSaleMaturityAndCollectionOfLongtermInvestments	1400000000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Amortized Cost Basis HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	2076000000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue	1920900000	usd
CY2022	wtm	Percentage Of Investments Recorded At Fair Value PercentageOfInvestmentsRecordedAtFairValue	0.72
CY2021	wtm	Percentage Of Investments Recorded At Fair Value PercentageOfInvestmentsRecordedAtFairValue	0.68
CY2022Q4	wtm	Investments Held In Trusts InvestmentsHeldInTrusts	500500000	usd
CY2021Q4	wtm	Investments Held In Trusts InvestmentsHeldInTrusts	479500000	usd
CY2022Q4	us-gaap	Assets Held By Insurance Regulators AssetsHeldByInsuranceRegulators	4600000	usd
CY2021Q4	us-gaap	Assets Held By Insurance Regulators AssetsHeldByInsuranceRegulators	4800000	usd
CY2022Q4	us-gaap	Other Long Term Investments OtherLongTermInvestments	1488000000	usd
CY2021Q4	us-gaap	Other Long Term Investments OtherLongTermInvestments	1377800000	usd
CY2022Q4	us-gaap	Goodwill Fair Value Disclosure GoodwillFairValueDisclosure	176500000	usd
CY2022Q4	us-gaap	Goodwill Goodwill	176500000	usd
CY2021Q4	us-gaap	Goodwill Fair Value Disclosure GoodwillFairValueDisclosure	142300000	usd
CY2021Q4	us-gaap	Goodwill Goodwill	142300000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Fair Value Disclosure FiniteLivedIntangibleAssetsFairValueDisclosure	404600000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	12200000	usd
CY2021Q4	us-gaap	Finite Lived Intangible Assets Fair Value Disclosure FiniteLivedIntangibleAssetsFairValueDisclosure	347500000	usd
CY2021Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	7000000.0	usd
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	5200000	usd
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	4600000	usd
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1600000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	7100000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	6600000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	5700000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	4800000	usd
CY2022Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	16000000.0	usd
CY2022Q4	wtm	Finite Lived Intangible Asset Expected Amortization FiniteLivedIntangibleAssetExpectedAmortization	40200000	usd
CY2022Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	175700000	usd
CY2022	us-gaap	Schedule Of Liability For Unpaid Claims And Claims Adjustment Expense ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense	The following table summarizes the loss and LAE reserve activity of Ark’s insurance and reinsurance subsidiaries for the year ended December 31, 2022 and 2021:<div style="text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:96.198%"><tr><td style="width:1.0%"/><td style="width:68.656%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.559%"/><td style="width:0.1%"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td style="width:1.0%"/><td style="width:13.337%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.407%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:13.341%"/><td style="width:0.1%"/></tr><tr><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="9" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">Year Ended December 31,</span></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">Millions</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">2022</span></td><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">2021</span></td></tr><tr><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Gross beginning balance</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td style="border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">$</span></td><td style="border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">894.7</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td style="border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">696.0 </span></td><td style="border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Less: beginning reinsurance recoverable on unpaid losses </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:100%;position:relative;top:-2.8pt;vertical-align:baseline">(1)</span></div></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(428.9)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(433.4)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt 2px 7pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Net loss and LAE reserves</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">465.8</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">262.6 </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Losses and LAE incurred relating to:</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%"> Current year losses</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">588.1</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">336.3 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%"> Prior year losses</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(51.7)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(21.5)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Net incurred losses and LAE</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">536.4</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">314.8 </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Loss and LAE paid relating to:</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt 2px 13pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Current year losses</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(98.9)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(43.9)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt 2px 7pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%"> Prior year losses</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(158.6)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(61.6)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Net paid losses and LAE</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(257.5)</span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(105.5)</span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Change in TPC Providers’ participation </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.85pt;font-weight:400;line-height:100%;position:relative;top:-3.15pt;vertical-align:baseline">(2)</span></div></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">57.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(2.2)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Foreign currency translation and other adjustments to loss and LAE reserves</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(10.7)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(3.9)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Net ending balance</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">791.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">465.8 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div style="padding-left:6pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Plus: ending reinsurance recoverable on unpaid losses </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:100%;position:relative;top:-2.8pt;vertical-align:baseline">(3)</span></div></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">505.0</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">428.9 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="border-bottom:3pt double #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:9pt;font-weight:400;line-height:100%">Gross ending balance</span></td><td colspan="3" style="border-bottom:3pt double #000;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">$</span></td><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">1,296.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="border-bottom:3pt double #000;padding:0 1pt"/><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">894.7 </span></td><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr></table></div><div style="margin-top:3pt;padding-left:13.5pt;padding-right:9pt;text-indent:-4.5pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(1)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%"> The beginning reinsurance recoverable on unpaid losses includes amounts attributable to TPC Providers of $276.8 and $319.2 as of December 31, 2021 and 2020.</span></div><div style="padding-left:13.5pt;padding-right:9pt;text-indent:-4.5pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(2)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%"> Amount represents the impact to net loss and LAE reserves due to a change in the TPC Providers’ participation related to the annual RITC process.</span></div><div style="padding-left:13.5pt;padding-right:9pt;text-indent:-4.5pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(3)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%"> The ending reinsurance recoverable on unpaid losses on unpaid losses includes amounts attributable to TPC Providers of $145.4 and $276.8 as of December 31, 2022 and 2021. </span></div><div style="text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:112%">The following table summarizes the unpaid loss and LAE reserves, net of reinsurance recoverables on unpaid losses, for each of Ark’s major reserving lines of business as of December 31, 2022 and 2021:</span></div><div style="text-indent:18pt"><span><br/></span></div><div style="text-indent:18pt"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:96.491%"><tr><td style="width:1.0%"/><td style="width:68.748%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.557%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:13.293%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.406%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:13.296%"/><td style="width:0.1%"/></tr><tr><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="9" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">Year Ended December 31,</span></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%"><br/><br/></span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">Millions</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">2022</span></td><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">2021</span></td></tr><tr><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Property and Accident & Health</span></td><td colspan="3" style="padding:0 1pt"/><td style="border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">$</span></td><td style="border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">258.2</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td style="border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">175.0 </span></td><td style="border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Specialty</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">204.3</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">85.2 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Marine & Energy</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">196.4</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">99.3 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Casualty - Active </span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">71.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">37.4 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Casualty - Runoff</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">60.8</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">68.4 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:112%">Other</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">.3</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">.5 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:112%"> Unpaid loss and LAE reserves, net of reinsurance recoverables on unpaid losses</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">791.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">465.8 </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Plus: Reinsurance recoverables on unpaid losses </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6.5pt;font-weight:400;line-height:100%;position:relative;top:-3.5pt;vertical-align:baseline">(1)</span></div></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Property and Accident & Health</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">224.6</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">145.2 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Specialty</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">97.2</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">68.9 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Marine & Energy</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">79.8</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">70.2 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Casualty - Active</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">49.9</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">41.4 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Casualty - Runoff</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">53.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">103.2 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div style="text-indent:9pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:112%">Total Reinsurance recoverables on unpaid losses </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6.5pt;font-weight:400;line-height:112%;position:relative;top:-3.5pt;vertical-align:baseline">(1)</span></div></td><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">505.0</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">428.9 </span></td><td style="border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="border-bottom:3pt double #000000;padding:2px 1pt 2px 13pt;text-align:left;text-indent:4.5pt;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Total unpaid loss and LAE reserves</span></td><td colspan="3" style="border-bottom:3pt double #000000;padding:0 1pt"/><td style="border-bottom:3pt double #000000;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">$</span></td><td style="border-bottom:3pt double #000000;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">1,296.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-bottom:3pt double #000000;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="border-bottom:3pt double #000;padding:0 1pt"/><td style="border-bottom:3pt double #000000;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="border-bottom:3pt double #000000;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">894.7 </span></td><td style="border-bottom:3pt double #000000;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr></table></div><div style="margin-top:3pt;padding-left:9pt;text-indent:9pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(1)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%"> The reinsurance recoverables on unpaid losses include amounts attributable to TPC Providers of $145.4 and $276.8 as of December 31, 2022 and 2021.</span></div>
CY2022Q4	us-gaap	Reinsurance Recoverables On Unpaid Losses Gross ReinsuranceRecoverablesOnUnpaidLossesGross	505000000	usd
CY2022Q4	us-gaap	Reinsurance Recoverables On Paid Losses Gross ReinsuranceRecoverablesOnPaidLossesGross	31100000	usd
CY2021Q4	us-gaap	Reinsurance Recoverables On Unpaid Losses Gross ReinsuranceRecoverablesOnUnpaidLossesGross	428900000	usd
CY2021Q4	us-gaap	Reinsurance Recoverables On Paid Losses Gross ReinsuranceRecoverablesOnPaidLossesGross	19500000	usd
CY2022Q4	us-gaap	Long Term Debt LongTermDebt	575200000	usd
CY2021Q4	us-gaap	Long Term Debt LongTermDebt	420900000	usd
CY2022Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	5400000	usd
CY2022Q4	us-gaap	Long Term Debt Maturing In Years Two And Three LongTermDebtMaturingInYearsTwoAndThree	12600000	usd
CY2022Q4	us-gaap	Long Term Debt Maturing In Years Four And Five LongTermDebtMaturingInYearsFourAndFive	30700000	usd
CY2022Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	542200000	usd
CY2022Q4	wtm	Long Term Debt Maturities Repayments Of Principal Total LongTermDebtMaturitiesRepaymentsOfPrincipalTotal	590900000	usd
CY2022Q4	wtm	Debt Covenant Loan To Value Maximum Percent Period One DebtCovenantLoanToValueMaximumPercentPeriodOne	0.50
CY2022Q4	wtm	Debt Covenant Loan To Value Maximum Percent Period Two DebtCovenantLoanToValueMaximumPercentPeriodTwo	0.40
CY2022Q4	wtm	Debt Covenant Loan To Value Maximum Percent Period Three DebtCovenantLoanToValueMaximumPercentPeriodThree	0.25
CY2022Q4	wtm	Debt Covenant Loan To Value Maximum Percent Period Four DebtCovenantLoanToValueMaximumPercentPeriodFour	0.15
CY2022Q4	wtm	Debt Covenant Loan To Value Maximum Percent Period Five DebtCovenantLoanToValueMaximumPercentPeriodFive	0
CY2022Q4	wtm	Debt Covenant Loan To Value Maximum Percent DebtCovenantLoanToValueMaximumPercent	0.33
CY2022	us-gaap	Interest Expense Debt InterestExpenseDebt	40300000	usd
CY2021	us-gaap	Interest Expense Debt InterestExpenseDebt	20500000	usd
CY2020	us-gaap	Interest Expense Debt InterestExpenseDebt	7400000	usd
CY2022	us-gaap	Interest Paid InterestPaid	30500000	usd
CY2021	us-gaap	Interest Paid InterestPaid	13900000	usd
CY2020	us-gaap	Interest Paid InterestPaid	6100000	usd
CY2022	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	7300000	usd
CY2022	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	16900000	usd
CY2021	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	4800000	usd
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	10700000	usd
CY2022	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	4500000	usd
CY2021	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	2100000	usd
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	4200000	usd
CY2022	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	7100000	usd
CY2021	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	2800000	usd
CY2020	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	800000	usd
CY2022	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	28500000	usd
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	9700000	usd
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	15700000	usd
CY2021	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	13900000	usd
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-21000000.0	usd
CY2022	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	1800000	usd
CY2021	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	7000000.0	usd
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-10100000	usd
CY2022	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	3800000	usd
CY2021	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	13800000	usd
CY2020	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	600000	usd
CY2022	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	12900000	usd
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	34700000	usd
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-30500000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	41400000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	44400000	usd
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-14800000	usd
CY2022	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	-31400000	usd
CY2021	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	-57500000	usd
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	138700000	usd
CY2022	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	41200000	usd
CY2021	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	78200000	usd
CY2020	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	-74300000	usd
CY2022	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	19600000	usd
CY2021	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	2000000.0	usd
CY2020	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	26600000	usd
CY2022	wtm	Effective Income Tax Rate Reconciliation Member Surplus Contribution Amount EffectiveIncomeTaxRateReconciliationMemberSurplusContributionAmount	6200000	usd
CY2021	wtm	Effective Income Tax Rate Reconciliation Member Surplus Contribution Amount EffectiveIncomeTaxRateReconciliationMemberSurplusContributionAmount	5600000	usd
CY2020	wtm	Effective Income Tax Rate Reconciliation Member Surplus Contribution Amount EffectiveIncomeTaxRateReconciliationMemberSurplusContributionAmount	4800000	usd
CY2022	wtm	Effective Income Tax Rate Reduction Withholding Tax Amount EffectiveIncomeTaxRateReductionWithholdingTaxAmount	3100000	usd
CY2021	wtm	Effective Income Tax Rate Reduction Withholding Tax Amount EffectiveIncomeTaxRateReductionWithholdingTaxAmount	300000	usd
CY2020	wtm	Effective Income Tax Rate Reduction Withholding Tax Amount EffectiveIncomeTaxRateReductionWithholdingTaxAmount	5000000.0	usd
CY2022	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	2800000	usd
CY2021	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	7300000	usd
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	8900000	usd
CY2022	us-gaap	Income Tax Reconciliation Nondeductible Expense Share Based Compensation Cost IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost	1000000.0	usd
CY2021	us-gaap	Income Tax Reconciliation Nondeductible Expense Share Based Compensation Cost IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost	1500000	usd
CY2020	us-gaap	Income Tax Reconciliation Nondeductible Expense Share Based Compensation Cost IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost	1100000	usd
CY2022	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	400000	usd
CY2021	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	10900000	usd
CY2020	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	-3100000	usd
CY2022	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	200000	usd
CY2021	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	200000	usd
CY2020	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	800000	usd
CY2022	us-gaap	Income Tax Reconciliation Disposition Of Business IncomeTaxReconciliationDispositionOfBusiness	0	usd
CY2021	us-gaap	Income Tax Reconciliation Disposition Of Business IncomeTaxReconciliationDispositionOfBusiness	0	usd
CY2020	us-gaap	Income Tax Reconciliation Disposition Of Business IncomeTaxReconciliationDispositionOfBusiness	-130500000	usd
CY2022	us-gaap	Income Tax Reconciliation Tax Contingencies IncomeTaxReconciliationTaxContingencies	0	usd
CY2021	us-gaap	Income Tax Reconciliation Tax Contingencies IncomeTaxReconciliationTaxContingencies	0	usd
CY2020	us-gaap	Income Tax Reconciliation Tax Contingencies IncomeTaxReconciliationTaxContingencies	-1900000	usd
CY2022	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-1300000	usd
CY2021	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-3700000	usd
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	10700000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	41400000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	44400000	usd
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-14800000	usd
CY2022	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	10300000	usd
CY2021	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-100000	usd
CY2020	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	15900000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Domestic DeferredTaxAssetsOperatingLossCarryforwardsDomestic	85400000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Domestic DeferredTaxAssetsOperatingLossCarryforwardsDomestic	85700000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Foreign DeferredTaxAssetsOperatingLossCarryforwardsForeign	36100000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Foreign DeferredTaxAssetsOperatingLossCarryforwardsForeign	46100000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits	21400000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits	14500000	usd
CY2022Q4	wtm	Deferred Tax Asset Accrued Interest DeferredTaxAssetAccruedInterest	8800000	usd
CY2021Q4	wtm	Deferred Tax Asset Accrued Interest DeferredTaxAssetAccruedInterest	7800000	usd
CY2022Q4	wtm	Deferred Tax Assets Deferred Expense Deferred Policy Acquisition Cost DeferredTaxAssetsDeferredExpenseDeferredPolicyAcquisitionCost	8000000.0	usd
CY2021Q4	wtm	Deferred Tax Assets Deferred Expense Deferred Policy Acquisition Cost DeferredTaxAssetsDeferredExpenseDeferredPolicyAcquisitionCost	6400000	usd
CY2022Q4	wtm	Deferred Tax Assets Unrealized Investment Gains Losses Net DeferredTaxAssetsUnrealizedInvestmentGainsLossesNet	4700000	usd
CY2021Q4	wtm	Deferred Tax Assets Unrealized Investment Gains Losses Net DeferredTaxAssetsUnrealizedInvestmentGainsLossesNet	0	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Other DeferredTaxAssetsTaxCreditCarryforwardsOther	1800000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Other DeferredTaxAssetsTaxCreditCarryforwardsOther	200000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	500000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	400000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	166700000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	161100000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	94300000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	85600000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	72400000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	75500000	usd
CY2022	wtm	Net Income Loss Attributableto Parent Basicand Diluted Earnings Per Share Numerators NetIncomeLossAttributabletoParentBasicandDilutedEarningsPerShareNumerators	-108400000	usd
CY2022Q4	wtm	Deferredtaxliabilitiesmemberssurpluscontributions Deferredtaxliabilitiesmemberssurpluscontributions	71300000	usd
CY2021Q4	wtm	Deferredtaxliabilitiesmemberssurpluscontributions Deferredtaxliabilitiesmemberssurpluscontributions	60400000	usd
CY2022Q4	wtm	Deferred Tax Liability Purchase Accounting DeferredTaxLiabilityPurchaseAccounting	43900000	usd
CY2021Q4	wtm	Deferred Tax Liability Purchase Accounting DeferredTaxLiabilityPurchaseAccounting	43900000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Investments DeferredTaxLiabilitiesInvestments	33900000	usd
CY2021Q4	us-gaap	Deferred Tax Liabilities Investments DeferredTaxLiabilitiesInvestments	26800000	usd
CY2022Q4	wtm	Deferred Tax Liabilities Deferred Underwriting DeferredTaxLiabilitiesDeferredUnderwriting	9700000	usd
CY2021Q4	wtm	Deferred Tax Liabilities Deferred Underwriting DeferredTaxLiabilitiesDeferredUnderwriting	4100000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Unrealized Gains On Trading Securities DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities	0	usd
CY2021Q4	us-gaap	Deferred Tax Liabilities Unrealized Gains On Trading Securities DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities	10700000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	1400000	usd
CY2021Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	1800000	usd
CY2022Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	160200000	usd
CY2021Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	147700000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	87800000	usd
CY2021Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	72200000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	94300000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	85600000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Foreign DeferredTaxAssetsTaxCreditCarryforwardsForeign	1800000	usd
CY2022	wtm	Percentage Of Likelihood For Realization Of Benefit Upon Ultimate Settlement PercentageOfLikelihoodForRealizationOfBenefitUponUltimateSettlement	0.50
CY2022Q4	wtm	Percentageof Risk Premium Ceded PercentageofRiskPremiumCeded	0.60
CY2018	wtm	Insurance Linked Securities Term InsuranceLinkedSecuritiesTerm	P12Y
CY2018	wtm	Insurance Linked Securities Callable Term InsuranceLinkedSecuritiesCallableTerm	P5Y
CY2021	wtm	Insurance Linked Securities Term InsuranceLinkedSecuritiesTerm	P12Y
CY2021	wtm	Insurance Linked Securities Callable Term InsuranceLinkedSecuritiesCallableTerm	P5Y
CY2022Q4	wtm	Insurance Linked Securities Term InsuranceLinkedSecuritiesTerm	P12Y
CY2022Q4	wtm	Insurance Linked Securities Callable Term InsuranceLinkedSecuritiesCallableTerm	P7Y
CY2022	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	792800000	usd
CY2021	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-275400000	usd
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	708700000	usd
CY2022	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-903200000	usd
CY2021	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	3900000	usd
CY2020	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	11800000	usd
CY2022	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Noncontrolling Interest IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToNoncontrollingInterest	-700000	usd
CY2021	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Noncontrolling Interest IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToNoncontrollingInterest	1000000.0	usd
CY2020	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Noncontrolling Interest IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToNoncontrollingInterest	200000	usd
CY2022	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	-109700000	usd
CY2021	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	-272500000	usd
CY2020	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	720300000	usd
CY2022	wtm	Income Loss Allocated To Participating Unvested Restricted Common Shares IncomeLossAllocatedToParticipatingUnvestedRestrictedCommonShares	-1300000	usd
CY2021	wtm	Income Loss Allocated To Participating Unvested Restricted Common Shares IncomeLossAllocatedToParticipatingUnvestedRestrictedCommonShares	-3200000	usd
CY2020	wtm	Income Loss Allocated To Participating Unvested Restricted Common Shares IncomeLossAllocatedToParticipatingUnvestedRestrictedCommonShares	9500000	usd
CY2021	wtm	Net Income Loss Attributableto Parent Basicand Diluted Earnings Per Share Numerators NetIncomeLossAttributabletoParentBasicandDilutedEarningsPerShareNumerators	-269300000	usd
CY2020	wtm	Net Income Loss Attributableto Parent Basicand Diluted Earnings Per Share Numerators NetIncomeLossAttributabletoParentBasicandDilutedEarningsPerShareNumerators	710800000	usd
CY2022	us-gaap	Weighted Average Number Of Shares Issued Basic WeightedAverageNumberOfSharesIssuedBasic	2862400	shares
CY2021	us-gaap	Weighted Average Number Of Shares Issued Basic WeightedAverageNumberOfSharesIssuedBasic	3079000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Issued Basic WeightedAverageNumberOfSharesIssuedBasic	3122200	shares
CY2022	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	36200	shares
CY2021	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	36500	shares
CY2020	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	40800	shares
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	2826200	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	3042500	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	3081400	shares
CY2022	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	2862400	shares
CY2021	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	3079000	shares
CY2020	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	3122200	shares
CY2022	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	36200	shares
CY2021	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	36500	shares
CY2020	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	40800	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	2826200	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	3042500	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	3081400	shares
CY2022	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.00
CY2021	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.00
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.00
CY2022	us-gaap	Earnings Per Share Diluted Undistributed EarningsPerShareDilutedUndistributed	-39.34
CY2021	us-gaap	Earnings Per Share Diluted Undistributed EarningsPerShareDilutedUndistributed	-89.52
CY2020	us-gaap	Earnings Per Share Diluted Undistributed EarningsPerShareDilutedUndistributed	229.69
CY2022	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-38.34
CY2022	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-38.34
CY2021	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-88.52
CY2021	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-88.52
CY2020	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	230.69
CY2020	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	230.69
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	3200000	usd
CY2022	wtm	Income Loss From Continuing Operatings Excluding Portion Attributable To Noncontrolling Interest Net IncomeLossFromContinuingOperatingsExcludingPortionAttributableToNoncontrollingInterestNet	-108400000	usd
CY2021	wtm	Income Loss From Continuing Operatings Excluding Portion Attributable To Noncontrolling Interest Net IncomeLossFromContinuingOperatingsExcludingPortionAttributableToNoncontrollingInterestNet	-269300000	usd
CY2020	wtm	Income Loss From Continuing Operatings Excluding Portion Attributable To Noncontrolling Interest Net IncomeLossFromContinuingOperatingsExcludingPortionAttributableToNoncontrollingInterestNet	710800000	usd
CY2022	wtm	Dividends Common Stock Cash Net Of Restricted Common Share Amounts DividendsCommonStockCashNetOfRestrictedCommonShareAmounts	3000000.0	usd
CY2021	wtm	Dividends Common Stock Cash Net Of Restricted Common Share Amounts DividendsCommonStockCashNetOfRestrictedCommonShareAmounts	3100000	usd
CY2020	wtm	Dividends Common Stock Cash Net Of Restricted Common Share Amounts DividendsCommonStockCashNetOfRestrictedCommonShareAmounts	3100000	usd
CY2022	us-gaap	Undistributed Earnings UndistributedEarnings	-111400000	usd
CY2021	us-gaap	Undistributed Earnings UndistributedEarnings	-272400000	usd
CY2020	us-gaap	Undistributed Earnings UndistributedEarnings	707700000	usd
CY2020	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	15745	shares
CY2022	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	3000000	usd
CY2022Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	25200000	usd
CY2021Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	28100000	usd
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	27100000	usd
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	30000000	usd
CY2022	us-gaap	Operating Lease Cost OperatingLeaseCost	8000000.0	usd
CY2021	us-gaap	Operating Lease Cost OperatingLeaseCost	6700000	usd
CY2022	us-gaap	Sublease Income SubleaseIncome	700000	usd
CY2021	us-gaap	Sublease Income SubleaseIncome	400000	usd
CY2022	us-gaap	Lease Cost LeaseCost	7300000	usd
CY2021	us-gaap	Lease Cost LeaseCost	6300000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	8700000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	7600000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	5100000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	2800000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	1600000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	3900000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	29700000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	2600000	usd
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	27100000	usd
CY2022Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	25200000	usd
CY2022Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.041
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	3100000	usd
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	27100000	usd
CY2021Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	28100000	usd
CY2021Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.040
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	30000000.0	usd
CY2022	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	615800000	usd
CY2022	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	1335.11
CY2022	us-gaap	Shares Paid For Tax Withholding For Share Based Compensation SharesPaidForTaxWithholdingForShareBasedCompensation	4011	shares
CY2022Q3	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	1400
CY2022Q3	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	460800000	usd
CY2021	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	107500000	usd
CY2021	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	1091.29
CY2021	us-gaap	Shares Paid For Tax Withholding For Share Based Compensation SharesPaidForTaxWithholdingForShareBasedCompensation	7218	shares
CY2020	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	85100000	usd
CY2020	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	858.81
CY2020	us-gaap	Shares Paid For Tax Withholding For Share Based Compensation SharesPaidForTaxWithholdingForShareBasedCompensation	5899	shares
CY2022	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	15640	shares
CY2021	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	15066	shares
CY2022	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.00
CY2022Q4	us-gaap	Minority Interest MinorityInterest	188100000	usd
CY2021Q4	us-gaap	Minority Interest MinorityInterest	156600000	usd
CY2022	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	3	segment
CY2022	us-gaap	Premiums Earned Net PremiumsEarnedNet	1076700000	usd
CY2022	us-gaap	Net Investment Income NetInvestmentIncome	124400000	usd
CY2022	wtm	Gain Loss On Investments Net Of Tax GainLossOnInvestmentsNetOfTax	-98500000	usd
CY2022	us-gaap	Gain Loss On Investments GainLossOnInvestments	-93000000.0	usd
CY2022	wtm	Commission Revenue CommissionRevenue	11500000	usd
CY2022	us-gaap	Other Income OtherIncome	136800000	usd
CY2022	us-gaap	Revenues Revenues	1157900000	usd
CY2022	wtm	Insurance Loss And Loss Adjustments Expense InsuranceLossAndLossAdjustmentsExpense	536400000	usd
CY2022	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	250600000	usd
CY2022	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	98600000	usd
CY2022	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	376200000	usd
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	5200000	usd
CY2022	us-gaap	Interest Expense Debt InterestExpenseDebt	40300000	usd
CY2022	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	1307300000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-149400000	usd
CY2021	us-gaap	Premiums Earned Net PremiumsEarnedNet	664200000	usd
CY2021	us-gaap	Net Investment Income NetInvestmentIncome	82500000	usd
CY2021	wtm	Gain Loss On Investments Net Of Tax GainLossOnInvestmentsNetOfTax	134200000	usd
CY2021	us-gaap	Gain Loss On Investments GainLossOnInvestments	-380300000	usd
CY2021	wtm	Commission Revenue CommissionRevenue	9600000	usd
CY2021	us-gaap	Other Income OtherIncome	104200000	usd
CY2021	us-gaap	Revenues Revenues	614400000	usd
CY2021	wtm	Insurance Loss And Loss Adjustments Expense InsuranceLossAndLossAdjustmentsExpense	314800000	usd
CY2021	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	186300000	usd
CY2021	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	69300000	usd
CY2021	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	292500000	usd
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	4600000	usd
CY2021	us-gaap	Interest Expense Debt InterestExpenseDebt	20500000	usd
CY2021	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	888000000.0	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-273600000	usd
CY2020	us-gaap	Premiums Earned Net PremiumsEarnedNet	22800000	usd
CY2020	us-gaap	Net Investment Income NetInvestmentIncome	131000000.0	usd
CY2020	wtm	Gain Loss On Investments Net Of Tax GainLossOnInvestmentsNetOfTax	30800000	usd
CY2020	us-gaap	Gain Loss On Investments GainLossOnInvestments	686000000.0	usd
CY2020	wtm	Commission Revenue CommissionRevenue	8300000	usd
CY2020	us-gaap	Other Income OtherIncome	16700000	usd
CY2020	us-gaap	Revenues Revenues	895600000	usd
CY2020	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	7000000.0	usd
CY2020	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	11300000	usd
CY2020	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	207900000	usd
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1600000	usd
CY2020	us-gaap	Interest Expense Debt InterestExpenseDebt	7400000	usd
CY2020	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	235200000	usd
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	660400000	usd
CY2022Q4	us-gaap	Investments Investments	5170000000	usd
CY2022Q4	us-gaap	Assets Assets	7389300000	usd
CY2022Q4	us-gaap	Liabilities Liabilities	3454300000	usd
CY2022Q4	us-gaap	Stockholders Equity StockholdersEquity	3746900000	usd
CY2022Q4	us-gaap	Minority Interest MinorityInterest	188100000	usd
CY2021Q4	us-gaap	Investments Investments	4257500000	usd
CY2021Q4	us-gaap	Assets Assets	7000700000	usd
CY2021Q4	us-gaap	Liabilities Liabilities	3296000000	usd
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	3548100000	usd
CY2021Q4	us-gaap	Minority Interest MinorityInterest	156600000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Reclassification Adjustment From Aoci Realized Upon Sale Or Liquidation Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax	-2900000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Reclassification Adjustment From Aoci Realized Upon Sale Or Liquidation Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax	0	usd
CY2020	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Reclassification Adjustment From Aoci Realized Upon Sale Or Liquidation Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax	0	usd
CY2022	dei	Auditor Name AuditorName	PricewaterhouseCoopers LLP
CY2022	dei	Auditor Location AuditorLocation	Atlanta, Georgia
CY2022Q4	us-gaap	Summary Of Investments Other Than Investments In Related Parties Cost SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost	5002600000	usd
CY2022Q4	us-gaap	Summary Of Investments Other Than Investments In Related Parties Carrying Amount SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount	5170000000	usd
CY2022Q4	us-gaap	Summary Of Investments Other Than Investments In Related Parties Fair Value SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue	5170000000	usd
CY2022	wtm	Amortizationof Restricted Sharesand Option Awards AmortizationofRestrictedSharesandOptionAwards	14000000.0	usd
CY2021	wtm	Amortizationof Restricted Sharesand Option Awards AmortizationofRestrictedSharesandOptionAwards	14700000	usd
CY2020	wtm	Amortizationof Restricted Sharesand Option Awards AmortizationofRestrictedSharesandOptionAwards	16600000	usd
CY2022	wtm	Increase Decrease In Payables From Receivables To Affiliates IncreaseDecreaseInPayablesFromReceivablesToAffiliates	3300000	usd
CY2021	wtm	Increase Decrease In Payables From Receivables To Affiliates IncreaseDecreaseInPayablesFromReceivablesToAffiliates	6500000	usd
CY2020	wtm	Increase Decrease In Payables From Receivables To Affiliates IncreaseDecreaseInPayablesFromReceivablesToAffiliates	4800000	usd

Files In Submission

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$WTM
WHITE MOUNTAINS INSURANCE GROUP LTD Stock $wtm

2023 Q1 Form 10-K Financial Statement

#000077686723000004 Filed on February 27, 2023

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$WTM WHITE MOUNTAINS INSURANCE GROUP LTD Stock $wtm

2023 Q1 Form 10-K Financial Statement

#000077686723000004 Filed on February 27, 2023

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$WTM
WHITE MOUNTAINS INSURANCE GROUP LTD Stock $wtm