Investments - Rollforward of Allowance for Debt Securities Credit Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance	$ 16	$ 43	$ 23	$ 9
Additions for which credit loss was not previously recorded	26	13	59	52
Changes for securities with previously recorded credit loss	2	(11)	4	(10)
Additions for purchases of PCD debt securities	0	0	0	0
Reductions from charge-offs	0	0	0	0
Reductions for securities disposed	(1)	(3)	(26)	(4)
Securities intended/required to be sold before recovery of amortized cost basis	(17)	(11)	(34)	(16)
Balance	26	31	26	31
Accrued interest receivable on debt securities	416	414	416	414
U.S. government securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance	0	0	0	0
Additions for which credit loss was not previously recorded	0	0	0	0
Changes for securities with previously recorded credit loss	0	0	0	0
Additions for purchases of PCD debt securities	0	0	0	0
Reductions from charge-offs	0	0	0	0
Reductions for securities disposed	0	0	0	0
Securities intended/required to be sold before recovery of amortized cost basis	0	0	0	0
Balance	0	0	0	0
Other government securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance	3	6	2	0
Additions for which credit loss was not previously recorded	2	0	2	6
Changes for securities with previously recorded credit loss	0	0	1	0
Additions for purchases of PCD debt securities	0	0	0	0
Reductions from charge-offs	0	0	0	0
Reductions for securities disposed	0	(3)	0	(3)
Securities intended/required to be sold before recovery of amortized cost basis	(2)	0	(2)	0
Balance	3	3	3	3
Public utilities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance	0	1	0	0
Additions for which credit loss was not previously recorded	0	0	0	1
Changes for securities with previously recorded credit loss	0	(1)	0	(1)
Additions for purchases of PCD debt securities	0	0	0	0
Reductions from charge-offs	0	0	0	0
Reductions for securities disposed	0	0	0	0
Securities intended/required to be sold before recovery of amortized cost basis	0	0	0	0
Balance	0	0	0	0
Corporate securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance	7	30	15	0
Additions for which credit loss was not previously recorded	15	12	48	42
Changes for securities with previously recorded credit loss	2	(8)	1	(3)
Additions for purchases of PCD debt securities	0	0	0	0
Reductions from charge-offs	0	0	0	0
Reductions for securities disposed	(1)	0	(24)	0
Securities intended/required to be sold before recovery of amortized cost basis	(6)	(11)	(23)	(16)
Balance	17	23	17	23
Residential mortgage-backed
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance	6	6	6	2
Additions for which credit loss was not previously recorded	0	1	0	3
Changes for securities with previously recorded credit loss	0	(2)	2	1
Additions for purchases of PCD debt securities	0	0	0	0
Reductions from charge-offs	0	0	0	0
Reductions for securities disposed	0	0	(2)	(1)
Securities intended/required to be sold before recovery of amortized cost basis	0	0	0	0
Balance	6	5	6	5
Commercial mortgage-backed
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance	0	0	0	0
Additions for which credit loss was not previously recorded	9	0	9	0
Changes for securities with previously recorded credit loss	0	0	0	0
Additions for purchases of PCD debt securities	0	0	0	0
Reductions from charge-offs	0	0	0	0
Reductions for securities disposed	0	0	0	0
Securities intended/required to be sold before recovery of amortized cost basis	(9)	0	(9)	0
Balance	0	0	0	0
Other asset-backed securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance	0	0	0	7
Additions for which credit loss was not previously recorded	0	0	0	0
Changes for securities with previously recorded credit loss	0	0	0	(7)
Additions for purchases of PCD debt securities	0	0	0	0
Reductions from charge-offs	0	0	0	0
Reductions for securities disposed	0	0	0	0
Securities intended/required to be sold before recovery of amortized cost basis	0	0	0	0
Balance	$ 0	$ 0	$ 0	$ 0