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Investments and Cash - Fixed Maturity Securities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investments
Percent of Total	100.00%	100.00%
Amortized Cost	$ 6,746	$ 7,707
Allowance for Credit Losses	(77)	(65)	$ (42)	$ (78)
Gross Unrealized Gains	55	65
Gross Unrealized Losses	(417)	(588)
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	$ 6,307	$ 7,119
Mortgage backed securities consisting of government-agency obligations, percent	42.00%	30.00%
Obligations of state and political subdivisions
Investments
Percent of Total	41.00%	45.00%
Amortized Cost	$ 2,733	$ 3,509
Allowance for Credit Losses	(13)	(14)
Gross Unrealized Gains	33	37
Gross Unrealized Losses	(92)	(138)
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	$ 2,661	$ 3,394
U.S. government and agencies
Investments
Percent of Total	1.00%	2.00%
Amortized Cost	$ 65	$ 118
Allowance for Credit Losses	0	0
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(6)	(8)
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	$ 60	$ 111
Corporate securities
Investments
Percent of Total	34.00%	31.00%
Amortized Cost	$ 2,327	$ 2,387
Allowance for Credit Losses	(6)	(6)
Gross Unrealized Gains	17	2
Gross Unrealized Losses	(197)	(299)
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	$ 2,141	$ 2,084
RMBS
Investments
Percent of Total	6.00%	5.00%
Amortized Cost	$ 428	$ 418
Allowance for Credit Losses	(21)	(19)
Gross Unrealized Gains	3	3
Gross Unrealized Losses	(68)	(62)
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	$ 342	$ 340
CMBS
Investments
Percent of Total	2.00%	4.00%
Amortized Cost	$ 157	$ 282
Allowance for Credit Losses	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(6)	(11)
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	$ 151	$ 271
CLOs
Investments
Percent of Total	7.00%	6.00%
Amortized Cost	$ 456	$ 449
Allowance for Credit Losses	0	0
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(7)	(21)
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	$ 450	$ 428
Others
Investments
Percent of Total	7.00%	5.00%
Amortized Cost	$ 465	$ 423
Allowance for Credit Losses	(37)	(26)
Gross Unrealized Gains	0	22
Gross Unrealized Losses	(26)	(26)
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	$ 402	$ 393
Non-U.S. government securities
Investments
Percent of Total	2.00%	2.00%
Amortized Cost	$ 115	$ 121
Allowance for Credit Losses	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(15)	(23)
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	$ 100	$ 98

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