Investments - Summary of Amounts Included in Net Realized (Losses) Gains and Other-Than-Temporary Impairments (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Investment [Line Items]
Foreign exchange (losses) gains			$ 14	$ (6)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	$ 0	$ 0	0	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Sell before Recovery	0	0	0	0
Realized Investment Gains (Losses)	14	3	31	4
Net realized (losses) gains			31	4
Fair Value of Securities Deposited in Connection wtih Letter of Credit	1		1		$ 1
Debt Securities, Available-for-sale, Realized Gain	6	1
Debt Securities, Available-for-sale, Realized Loss	1	0
Gross realized gains on securities			29	9
Available-for-sale Securities, Gross Realized Losses			(17)	(2)
Gain (Loss) on Investments [Member]
Investment [Line Items]
Foreign exchange (losses) gains	$ 9	$ 3	$ 20	$ (3)

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