Investments in Debt and Equity Securities - Summary of Investments In An Unrealized Loss Position That Are Not Other-Than-Temporarily Impaired (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	$ 377	$ 875
Less than 12 months - Unrealized losses	2	6
12 months or more - Fair Value	1,104	1,290
12 months or more - Unrealized losses	53	75
Fair Value	1,481	2,165
Unrealized Losses	55	81
Other U.S. and non-U.S. government bonds
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	0	0
Less than 12 months - Unrealized losses	0	0
12 months or more - Fair Value	35	55
12 months or more - Unrealized losses	2	4
Fair Value	35	55
Unrealized Losses	2	4
Corporate bonds and other debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	242	729
Less than 12 months - Unrealized losses	1	3
12 months or more - Fair Value	655	812
12 months or more - Unrealized losses	22	33
Fair Value	897	1,541
Unrealized Losses	23	36
Asset-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	63	7
Less than 12 months - Unrealized losses	0	0
12 months or more - Fair Value	47	37
12 months or more - Unrealized losses	1	2
Fair Value	110	44
Unrealized Losses	1	2
U.S. governmental agency
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	67	126
Less than 12 months - Unrealized losses	1	3
12 months or more - Fair Value	265	273
12 months or more - Unrealized losses	24	30
Fair Value	332	399
Unrealized Losses	25	33
Commercial
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	5	13
Less than 12 months - Unrealized losses	0	0
12 months or more - Fair Value	102	113
12 months or more - Unrealized losses	4	6
Fair Value	107	126
Unrealized Losses	$ 4	$ 6

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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