Reserve for Future Policy Benefits and Contractholder Funds - Schedule of Rollforward of Reserve for Future Policy Benefits (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Present value of expected net premiums
Beginning balance	$ 2,013	$ 1,702
Beginning balance at original discount rate	2,067	1,795
Effect of changes in cash flow assumptions			$ (1)	$ (12)
Effect of actual variances from expected experience			(14)	(7)
Adjusted beginning balance			2,052	1,776
Issuances	400	277
Interest accrual	46	30
Net premiums collected	(228)	(211)
Ending balance at original discount rate	2,270	1,872
Effect of changes in discount rate assumptions	(87)	(75)
Ending balance	2,183	1,797
Present value of expected future policy benefits
Beginning balance	3,110	2,753
Beginning balance at original discount rate	3,151	2,850
Effect of changes in cash flow assumptions			(6)	(12)
Effect of actual variances from expected experience			(17)	(10)
Adjusted beginning balance			3,128	2,828
Issuances	401	274
Interest accrual	68	59
Benefit payments	(229)	(225)
Ending balance at original discount rate	3,368	2,936
Effect of changes in discount rate assumptions	(104)	(71)
Ending balance	3,264	2,865
Net reserve for future policy benefits	1,081	1,068
Less: reinsurance recoverables	81	86
Net reserve for future policy benefits, after reinsurance recoverables	1,000	982
Reserves related to short-duration contracts	263	271
Accident and health insurance
Present value of expected net premiums
Beginning balance	1,688	1,464
Beginning balance at original discount rate	1,737	1,549
Effect of changes in cash flow assumptions			(1)	0
Effect of actual variances from expected experience			(27)	(26)
Adjusted beginning balance			1,709	1,523
Issuances	344	259
Interest accrual	39	25
Net premiums collected	(196)	(186)
Ending balance at original discount rate	1,896	1,621
Effect of changes in discount rate assumptions	(79)	(68)
Ending balance	1,817	1,553
Present value of expected future policy benefits
Beginning balance	2,453	2,229
Beginning balance at original discount rate	2,495	2,316
Effect of changes in cash flow assumptions			(6)	0
Effect of actual variances from expected experience			(25)	(30)
Adjusted beginning balance			2,464	2,286
Issuances	344	256
Interest accrual	53	47
Benefit payments	(210)	(199)
Ending balance at original discount rate	2,651	2,390
Effect of changes in discount rate assumptions	(84)	(64)
Ending balance	2,567	2,326
Net reserve for future policy benefits	750	773
Less: reinsurance recoverables	80	84
Net reserve for future policy benefits, after reinsurance recoverables	670	689
Traditional life
Present value of expected net premiums
Beginning balance	325	238
Beginning balance at original discount rate	330	246
Effect of changes in cash flow assumptions			0	(12)
Effect of actual variances from expected experience			13	19
Adjusted beginning balance			343	253
Issuances	56	18
Interest accrual	7	5
Net premiums collected	(32)	(25)
Ending balance at original discount rate	374	251
Effect of changes in discount rate assumptions	(8)	(7)
Ending balance	366	244
Present value of expected future policy benefits
Beginning balance	657	524
Beginning balance at original discount rate	656	534
Effect of changes in cash flow assumptions			0	(12)
Effect of actual variances from expected experience			8	20
Adjusted beginning balance			$ 664	$ 542
Issuances	57	18
Interest accrual	15	12
Benefit payments	(19)	(26)
Ending balance at original discount rate	717	546
Effect of changes in discount rate assumptions	(20)	(7)
Ending balance	697	539
Net reserve for future policy benefits	331	295
Less: reinsurance recoverables	1	2
Net reserve for future policy benefits, after reinsurance recoverables	$ 330	$ 293