Other Insurance Liabilities and Separate Accounts - Changes in Liability for Future Policy Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Present value of expected future policy benefits
Effect of changes in discount rate assumptions	$ 2	$ (23)	$ (1)	$ (23)
Large Case Pensions
Present value of expected future policy benefits
Liability for future policy benefits, beginning of the period - current discount rate	1,917	2,139
Beginning liability for future policy benefits at original (locked-in) discount rate	2,090	2,251
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected experience			(4)	(8)
Adjusted beginning liability for future policy benefits - original (locked-in) discount rate			2,086	2,243
Issuances	9	20
Interest accrual (using locked-in discount rate)	21	24
Benefit payments (actual)	(61)	(63)
Ending liability for future policy benefits at original (locked-in) discount rate	2,055	2,224
Effect of changes in discount rate assumptions	(151)	(151)
Liability for future policy benefits, end of the period - current discount rate	1,904	2,073
Net liability for future policy benefits	1,904	2,073
Less: Reinsurance recoverable	0	0
Net liability for future policy benefits, net of reinsurance recoverable	1,904	2,073
Long-Term Care
Present value of expected net premiums
Liability for future policy benefits, beginning of the period - current discount rate	275	293
Beginning liability for future policy benefits at original (locked-in) discount rate	280	288
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected experience			1	5
Adjusted beginning liability for future policy benefits - original (locked-in) discount rate			281	293
Interest accrual (using locked-in discount rate)	3	4
Net premiums (actual)	(10)	(10)
Ending liability for future policy benefits at original (locked-in) discount rate	274	287
Effect of changes in discount rate assumptions	(2)	(2)
Liability for future policy benefits, end of the period - current discount rate	272	285
Present value of expected future policy benefits
Liability for future policy benefits, beginning of the period - current discount rate	1,552	1,640
Beginning liability for future policy benefits at original (locked-in) discount rate	1,647	1,632
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected experience			(2)	0
Adjusted beginning liability for future policy benefits - original (locked-in) discount rate			$ 1,645	$ 1,632
Issuances	0	0
Interest accrual (using locked-in discount rate)	20	21
Benefit payments (actual)	(19)	(18)
Ending liability for future policy benefits at original (locked-in) discount rate	1,646	1,635
Effect of changes in discount rate assumptions	(77)	(41)
Liability for future policy benefits, end of the period - current discount rate	1,569	1,594
Net liability for future policy benefits	1,297	1,309
Less: Reinsurance recoverable	0	0
Net liability for future policy benefits, net of reinsurance recoverable	$ 1,297	$ 1,309