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	Jun. 30, 2026	Dec. 31, 2025
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	$ 1,692	$ 177
Less than 12 months - Unrealized losses	5	0
12 months or more - Fair Value	738	763
12 months or more - Unrealized losses	30	26
Fair Value	2,430	940
Unrealized Losses	35	26
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	26	17
12 months or more - Unrealized losses	1	0
Fair Value	26	17
Unrealized Losses	1	0
Corporate bonds and other debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	1,427	130
Less than 12 months - Unrealized losses	1	0
12 months or more - Fair Value	352	306
12 months or more - Unrealized losses	7	6
Fair Value	1,779	436
Unrealized Losses	8	6
Asset-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	47	38
Less than 12 months - Unrealized losses	0	0
12 months or more - Fair Value	52	43
12 months or more - Unrealized losses	1	1
Fair Value	99	81
Unrealized Losses	1	1
U.S. governmental agency
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	173	3
Less than 12 months - Unrealized losses	3	0
12 months or more - Fair Value	214	307
12 months or more - Unrealized losses	17	15
Fair Value	387	310
Unrealized Losses	20	15
Residential
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	4	1
12 months or more - Unrealized losses	1	1
Fair Value	4	1
Unrealized Losses	1	1
Commercial
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	45	6
Less than 12 months - Unrealized losses	1	0
12 months or more - Fair Value	90	89
12 months or more - Unrealized losses	3	3
Fair Value	135	95
Unrealized Losses	$ 4	$ 3

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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