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Amount of increase in allowance for credit loss on reinsurance recoverable, from recovery.

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Amount of expense (reversal of expense) for expected credit loss on reinsurance recoverable.

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Amount of allowance for credit loss on reinsurance recoverable.

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Reinsurance - Allowance for Credit Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	$ 105	$ 99	$ 108		$ 114
Reinsurance Recoverable, Credit Loss Expense (Reversal)	0	(9)	4
Reinsurance, Loss on Uncollectible Accounts in Period, Amount	0	(1)	0
Reinsurance Recoverable, Allowance for Credit Loss, Recovery	0	0	1
Cumulative Effect, Period of Adoption, Adjustment [Member] \| Accounting Standards Update 2016-13 [Member]
Reinsurance Recoverable, Past Due [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest					2
Reinsurance Policy, Type [Axis]: Before Uncollectible Reinsurance [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	45	45	55		48
Reinsurance Policy, Type [Axis]: Before Uncollectible Reinsurance [Member] \| Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss					50
Reinsurance Policy, Type [Axis]: Disputes [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	60	54	53		114
Reinsurance Policy, Type [Axis]: Disputes [Member] \| Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss				$ 116
Reinsurance Policy, Type [Axis]: Disputes [Members]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss		54	53		66
Operating Segments \| Property and Casualty Insurance Subsidiaries
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	102	96	105		114
Reinsurance Recoverable, Credit Loss Expense (Reversal)	0	(9)	3
Reinsurance, Loss on Uncollectible Accounts in Period, Amount	0	(1)	0
Reinsurance Recoverable, Allowance for Credit Loss, Recovery	0	0	1
Operating Segments \| Property and Casualty Insurance Subsidiaries \| Cumulative Effect, Period of Adoption, Adjustment [Member] \| Accounting Standards Update 2016-13 [Member]
Reinsurance Recoverable, Past Due [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest					0
Operating Segments \| Property and Casualty Insurance Subsidiaries \| Reinsurance Policy, Type [Axis]: Before Uncollectible Reinsurance [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	42	42	52		48
Operating Segments \| Property and Casualty Insurance Subsidiaries \| Reinsurance Policy, Type [Axis]: Before Uncollectible Reinsurance [Member] \| Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss					48
Operating Segments \| Property and Casualty Insurance Subsidiaries \| Reinsurance Policy, Type [Axis]: Disputes [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	60	54	53		66
Operating Segments \| Group Insurance Policy [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	1	1	1		0
Reinsurance Recoverable, Credit Loss Expense (Reversal)	0	0	0
Reinsurance, Loss on Uncollectible Accounts in Period, Amount	0	0	0
Reinsurance Recoverable, Allowance for Credit Loss, Recovery	0	0	0
Operating Segments \| Group Insurance Policy [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member] \| Accounting Standards Update 2016-13 [Member]
Reinsurance Recoverable, Past Due [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest					1
Operating Segments \| Group Insurance Policy [Member] \| Reinsurance Policy, Type [Axis]: Before Uncollectible Reinsurance [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	1	1	1		0
Operating Segments \| Group Insurance Policy [Member] \| Reinsurance Policy, Type [Axis]: Before Uncollectible Reinsurance [Member] \| Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss					1
Operating Segments \| Group Insurance Policy [Member] \| Reinsurance Policy, Type [Axis]: Disputes [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	0	0	0
Operating Segments \| Group Insurance Policy [Member] \| Reinsurance Policy, Type [Axis]: Disputes [Members]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss		0	0		0
Corporate
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	2	2	2		0
Reinsurance Recoverable, Credit Loss Expense (Reversal)	0	0	1
Reinsurance, Loss on Uncollectible Accounts in Period, Amount	0	0	0
Reinsurance Recoverable, Allowance for Credit Loss, Recovery	0	0	0
Corporate \| Cumulative Effect, Period of Adoption, Adjustment [Member] \| Accounting Standards Update 2016-13 [Member]
Reinsurance Recoverable, Past Due [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest					1
Corporate \| Reinsurance Policy, Type [Axis]: Before Uncollectible Reinsurance [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	2	2	2		0
Corporate \| Reinsurance Policy, Type [Axis]: Before Uncollectible Reinsurance [Member] \| Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss					1
Corporate \| Reinsurance Policy, Type [Axis]: Disputes [Member]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss	$ 0	0	0
Corporate \| Reinsurance Policy, Type [Axis]: Disputes [Members]
Reinsurance Recoverable, Past Due [Line Items]
Reinsurance Recoverable, Allowance for Credit Loss		$ 0	$ 0		$ 0