Investments - Additional Information (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss	$ 2	$ 0	$ 0
Securities fair value	24	23
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 122	106
Average Percentage of Unrealized Loss Versus Amortized Cost for Below Investment Grade Securities	4.00%
Average Percentage of Unrealized Loss Versus Amortized Cost for Investment Grade Securities	9.00%
Fiduciary Funds Held by Insurance Distribution Subsidiaries	$ 2	0
Investment Portfolio [Member]
Schedule of Investments [Line Items]
Fair Value of Cash and Securities Pledged to Derivative Counterparties	27	64
Fixed Income Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss	2	0
Debt Securities, Available-for-sale, Unrealized Loss Position	1,306	1,183
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	122	106
Fixed Income Securities [Member] \| Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position	648	559
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	65	63
Fixed Income Securities [Member] \| Corporate Debt Securities [Member] \| External Credit Rating, Investment Grade
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	64
Fixed Income Securities [Member] \| Corporate Debt Securities [Member] \| External Credit Rating, Non Investment Grade [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	1
Fixed Income Securities [Member] \| Residential Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss	2	0
Debt Securities, Available-for-sale, Unrealized Loss Position	165	132
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	28	19
Fixed Income Securities [Member] \| Asset-backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position	154	203
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	11	5
Reported Value Measurement [Member]
Schedule of Investments [Line Items]
Other investments	87	61
Reported Value Measurement [Member] \| Interest Rate Contract [Member]
Schedule of Investments [Line Items]
Other investments	$ 35	$ 0

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