Policyholder Account Balances, Future Policy Benefits and Claims - Additional Liabilities (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Additional Liability, Long-Duration Insurance [Roll Forward]
Beginning balance	$ 1,321	$ 1,186
Interest accrual	10	41
Benefit accrual	36	138
Benefit payments	(17)	(72)
Effect of actual variances from expected experience	(3)	(4)
Impact of change in net unrealized (gains) losses on securities	(11)	32
Ending balance	1,336	1,321
Universal Life Insurance
Additional Liability, Long-Duration Insurance [Roll Forward]
Beginning balance	1,225	1,100
Interest accrual	9	35
Benefit accrual	33	128
Benefit payments	(13)	(50)
Effect of actual variances from expected experience	(3)	(13)
Impact of change in net unrealized (gains) losses on securities	(9)	25
Ending balance	$ 1,242	$ 1,225
Weighted average interest accretion rate	3.00%	3.00%
Weighted average discount rate	3.20%	3.20%
Weighted average duration of reserves (in years)	10 years	10 years
Variable Universal Life Insurance
Additional Liability, Long-Duration Insurance [Roll Forward]
Beginning balance	$ 81	$ 74
Interest accrual	1	5
Benefit accrual	2	8
Benefit payments	(3)	(18)
Effect of actual variances from expected experience	0	11
Impact of change in net unrealized (gains) losses on securities	0	1
Ending balance	$ 81	$ 81
Weighted average interest accretion rate	7.10%	6.90%
Weighted average discount rate	7.10%	7.10%
Weighted average duration of reserves (in years)	8 years	8 years
Other Life Insurance
Additional Liability, Long-Duration Insurance [Roll Forward]
Beginning balance	$ 15	$ 12
Interest accrual	0	1
Benefit accrual	1	2
Benefit payments	(1)	(4)
Effect of actual variances from expected experience	0	(2)
Impact of change in net unrealized (gains) losses on securities	(2)	6
Ending balance	$ 13	$ 15
Weighted average interest accretion rate	3.90%	4.00%
Weighted average discount rate	4.00%	4.00%
Weighted average duration of reserves (in years)	6 years	6 years