Investments - Current and Long-Term Fixed Maturity Securities, Available-For-Sale (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	$ 26,889	$ 26,928
Gross Unrealized Gains	631	284
Gross Unrealized Losses	(494)	(970)
Allowance For Credit Losses	(21)	(6)
Estimated Fair Value	27,005	26,236
United States Government securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	1,512	1,907
Gross Unrealized Gains	10	2
Gross Unrealized Losses	(19)	(85)
Allowance For Credit Losses	0	0
Estimated Fair Value	1,503	1,824
Government sponsored securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	80	156
Gross Unrealized Gains	2	0
Gross Unrealized Losses	(1)	(5)
Allowance For Credit Losses	0	0
Estimated Fair Value	81	151
Foreign government securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	13	19
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(2)
Allowance For Credit Losses	0	0
Estimated Fair Value	13	17
States, municipalities and political subdivisions, tax-exempt
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	3,701	3,142
Gross Unrealized Gains	76	33
Gross Unrealized Losses	(74)	(123)
Allowance For Credit Losses	(2)	0
Estimated Fair Value	3,701	3,052
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	13,498	14,095
Gross Unrealized Gains	419	192
Gross Unrealized Losses	(130)	(367)
Allowance For Credit Losses	(4)	(4)
Estimated Fair Value	13,783	13,916
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	3,203	3,274
Gross Unrealized Gains	43	13
Gross Unrealized Losses	(136)	(236)
Allowance For Credit Losses	(3)	0
Estimated Fair Value	3,107	3,051
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	2,078	1,801
Gross Unrealized Gains	28	8
Gross Unrealized Losses	(31)	(60)
Allowance For Credit Losses	(2)	(1)
Estimated Fair Value	2,073	1,748
Other asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost	2,804	2,534
Gross Unrealized Gains	53	36
Gross Unrealized Losses	(103)	(92)
Allowance For Credit Losses	(10)	(1)
Estimated Fair Value	$ 2,744	$ 2,477