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Investments and Cash - Fixed Maturity Securities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Investments
Percent of Total	100.00%	100.00%
Amortized Cost	$ 6,827	$ 6,746
Allowance for Credit Losses	(60)	(77)	$ (65)	$ (42)
Gross Unrealized Gains	44	55
Gross Unrealized Losses	(442)	(417)
Fixed-maturity securities, available-for-sale	$ 6,369	$ 6,307
Mortgage backed securities consisting of government-agency obligations, percent	68.00%	42.00%
Obligations of state and political subdivisions
Investments
Percent of Total	30.00%	41.00%
Amortized Cost	$ 2,032	$ 2,733
Allowance for Credit Losses	(14)	(13)
Gross Unrealized Gains	25	33
Gross Unrealized Losses	(103)	(92)
Fixed-maturity securities, available-for-sale	$ 1,940	$ 2,661
U.S. government and agencies
Investments
Percent of Total	1.00%	1.00%
Amortized Cost	$ 72	$ 65
Allowance for Credit Losses	0	0
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(6)	(6)
Fixed-maturity securities, available-for-sale	$ 67	$ 60
Corporate securities
Investments
Percent of Total	38.00%	34.00%
Amortized Cost	$ 2,586	$ 2,327
Allowance for Credit Losses	(7)	(6)
Gross Unrealized Gains	9	17
Gross Unrealized Losses	(206)	(197)
Fixed-maturity securities, available-for-sale	$ 2,382	$ 2,141
RMBS
Investments
Percent of Total	9.00%	6.00%
Amortized Cost	$ 657	$ 428
Allowance for Credit Losses	(21)	(21)
Gross Unrealized Gains	2	3
Gross Unrealized Losses	(71)	(68)
Fixed-maturity securities, available-for-sale	$ 567	$ 342
CMBS
Investments
Percent of Total	3.00%	2.00%
Amortized Cost	$ 189	$ 157
Allowance for Credit Losses	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(3)	(6)
Fixed-maturity securities, available-for-sale	$ 186	$ 151
CLOs
Investments
Percent of Total	9.00%	7.00%
Amortized Cost	$ 615	$ 456
Allowance for Credit Losses	(1)	0
Gross Unrealized Gains	6	1
Gross Unrealized Losses	(9)	(7)
Fixed-maturity securities, available-for-sale	$ 611	$ 450
Others
Investments
Percent of Total	9.00%	7.00%
Amortized Cost	$ 593	$ 465
Allowance for Credit Losses	(17)	(37)
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(30)	(26)
Fixed-maturity securities, available-for-sale	547	402
Others | Affiliated Entity
Investments
Amortized Cost	41	21
Fixed-maturity securities, available-for-sale	$ 42	$ 21
Non-U.S. government securities
Investments
Percent of Total	1.00%	2.00%
Amortized Cost	$ 83	$ 115
Allowance for Credit Losses	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(14)	(15)
Fixed-maturity securities, available-for-sale	$ 69	$ 100

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