Investments - Additional Information (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss	$ 0	$ 0	$ 0
Securities fair value	22	17
Debt Securities, Available-for-sale, Unrealized Loss Position	1,283	810
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	116	16
Interest Rate Contract [Member]
Schedule of Investments [Line Items]
Other investments	69	78
Fixed Income 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	1,198	682
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	116	16
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	614	380
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	69	9
Fixed Income Securities [Member] \| Corporate Debt Securities [Member] \| External Credit Rating, Investment Grade
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position	510
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	65
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, Unrealized Loss Position	104
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	4
Fixed Income Securities [Member] \| Residential Mortgage-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	116	2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	17	0
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	201	6
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	8	0
Reported Value Measurement [Member]
Schedule of Investments [Line Items]
Other investments	64	$ 106
Commitments [Member] \| Partnership Interest [Member]
Schedule of Investments [Line Items]
Other investments	$ 60

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