Future Policy Benefits - Schedule of Revenue and Interest Expense in Respect of Future Policy Benefits (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Disclosure In Tabular Form Of Revenue And Interest Expense In Respect Of Future Policy Benefits [Line Items]
Gross premiums	$ 770	$ 779	$ 1,538	$ 1,553	$ 3,141
Interest accretion	771	764	1,541	1,530	3,065
Long-term care insurance
Disclosure In Tabular Form Of Revenue And Interest Expense In Respect Of Future Policy Benefits [Line Items]
Gross premiums	627	626	1,250	1,245	2,544
Interest accretion	614	599	1,225	1,197	2,406
Life insurance
Disclosure In Tabular Form Of Revenue And Interest Expense In Respect Of Future Policy Benefits [Line Items]
Gross premiums	143	153	288	308	597
Interest accretion	8	10	16	22	42
Fixed annuities
Disclosure In Tabular Form Of Revenue And Interest Expense In Respect Of Future Policy Benefits [Line Items]
Gross premiums	0	0	0	0	0
Interest accretion	$ 149	$ 155	$ 300	$ 311	$ 617