Investments - Aggregate Fair Value and Gross Unrealized Loss of Fixed Maturity Securities in an Unrealized Loss Position (Details) $ in Millions	Dec. 31, 2025 USD ($) security	Dec. 31, 2024 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	1,207	2,559
Estimated fair value, less than 12 months	$ 3,594	$ 9,213
Gross unrealized loss, less than 12 months	$ (71)	$ (218)
Number of securities, 12 months or greater | security	2,946	3,886
Estimated fair value, 12 months or greater	$ 4,208	$ 6,649
Gross unrealized loss, 12 months or greater	$ (423)	$ (752)
United States Government securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	18	40
Estimated fair value, less than 12 months	$ 460	$ 1,240
Gross unrealized loss, less than 12 months	$ (3)	$ (52)
Number of securities, 12 months or greater | security	17	25
Estimated fair value, 12 months or greater	$ 167	$ 330
Gross unrealized loss, 12 months or greater	$ (16)	$ (33)
Government sponsored securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	4	10
Estimated fair value, less than 12 months	$ 0	$ 89
Gross unrealized loss, less than 12 months	$ 0	$ (2)
Number of securities, 12 months or greater | security	16	36
Estimated fair value, 12 months or greater	$ 29	$ 42
Gross unrealized loss, 12 months or greater	$ (1)	$ (3)
Foreign government securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	1	2
Estimated fair value, less than 12 months	$ 3	$ 15
Gross unrealized loss, less than 12 months	$ 0	$ (1)
Number of securities, 12 months or greater | security	2	2
Estimated fair value, 12 months or greater	$ 1	$ 2
Gross unrealized loss, 12 months or greater	$ 0	$ (1)
States, municipalities and political subdivisions, tax-exempt
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	213	527
Estimated fair value, less than 12 months	$ 486	$ 1,092
Gross unrealized loss, less than 12 months	$ (8)	$ (22)
Number of securities, 12 months or greater | security	522	661
Estimated fair value, 12 months or greater	$ 848	$ 943
Gross unrealized loss, 12 months or greater	$ (66)	$ (101)
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	568	1,415
Estimated fair value, less than 12 months	$ 1,398	$ 4,717
Gross unrealized loss, less than 12 months	$ (22)	$ (92)
Number of securities, 12 months or greater | security	839	1,317
Estimated fair value, 12 months or greater	$ 1,397	$ 2,645
Gross unrealized loss, 12 months or greater	$ (108)	$ (275)
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	169	306
Estimated fair value, less than 12 months	$ 282	$ 1,097
Gross unrealized loss, less than 12 months	$ (4)	$ (25)
Number of securities, 12 months or greater | security	1,164	1,312
Estimated fair value, 12 months or greater	$ 1,012	$ 1,291
Gross unrealized loss, 12 months or greater	$ (132)	$ (211)
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	80	136
Estimated fair value, less than 12 months	$ 308	$ 670
Gross unrealized loss, less than 12 months	$ (6)	$ (15)
Number of securities, 12 months or greater | security	212	297
Estimated fair value, 12 months or greater	$ 479	$ 661
Gross unrealized loss, 12 months or greater	$ (25)	$ (45)
Other asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	154	123
Estimated fair value, less than 12 months	$ 657	$ 293
Gross unrealized loss, less than 12 months	$ (28)	$ (9)
Number of securities, 12 months or greater | security	174	236
Estimated fair value, 12 months or greater	$ 275	$ 735
Gross unrealized loss, 12 months or greater	$ (75)	$ (83)