Investments -Schedule of Investments (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 3,946	$ 3,988
Gross Unrealized Gains	29	52
Gross Unrealized Losses	38	32
Estimated Fair Value	3,937	4,008
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,398	2,437
Gross Unrealized Gains	17	35
Gross Unrealized Losses	11	7
Estimated Fair Value	2,404	2,465
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	979	963
Gross Unrealized Gains	8	11
Gross Unrealized Losses	23	21
Estimated Fair Value	964	953
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	347	363
Gross Unrealized Gains	2	3
Gross Unrealized Losses	2	2
Estimated Fair Value	347	364
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	155	158
Gross Unrealized Gains	2	2
Gross Unrealized Losses	1	1
Estimated Fair Value	156	159
U.S. Treasury notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	20	20
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	20	20
Other
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	47	47
Gross Unrealized Gains	0	1
Gross Unrealized Losses	1	1
Estimated Fair Value	$ 46	$ 47

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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