Insurance Liabilities - Balances and Changes in Policyholder Contract Deposits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Policyholder Account Balance [Roll Forward]
Policyholder contract deposits	$ 163,698		$ 161,979
Life and Retirement
Policyholder Account Balance [Roll Forward]
Policyholder contract deposits account balance, beginning of year	165,033	$ 160,003	163,408	$ 158,494
Deposits	7,443	7,210
Policy charges	(717)	(771)
Surrenders and withdrawals	(7,191)	(5,666)
Benefit payments	(1,594)	(1,897)
Net transfers from (to) separate account	2,250	1,762
Interest credited	1,437	883
Other	(3)	(12)
Other reconciling items	(1,335)	(2,107)
Policyholder contract deposits	163,698	157,896
Cash surrender value	142,864	139,467
Life and Retirement | Individual Retirement
Policyholder Account Balance [Roll Forward]
Policyholder contract deposits account balance, beginning of year	96,288	91,070	94,896	89,554
Deposits	4,878	4,864
Policy charges	(186)	(244)
Surrenders and withdrawals	(4,600)	(3,171)
Benefit payments	(761)	(1,036)
Net transfers from (to) separate account	1,248	728
Interest credited	816	377
Other	(3)	(2)
Other reconciling items	(1,225)	(1,889)
Policyholder contract deposits	$ 95,063	$ 89,181
Weighted average crediting rate	2.86%	2.52%
Cash surrender value	$ 89,795	$ 84,906
Life and Retirement | Group Retirement
Policyholder Account Balance [Roll Forward]
Policyholder contract deposits account balance, beginning of year	40,895	42,903	41,299	43,395
Deposits	1,349	1,326
Policy charges	(122)	(110)
Surrenders and withdrawals	(2,466)	(2,016)
Benefit payments	(494)	(557)
Net transfers from (to) separate account	1,024	592
Interest credited	303	270
Other	2	3
Other reconciling items	(192)	(279)
Policyholder contract deposits	$ 40,703	$ 42,624
Weighted average crediting rate	3.05%	2.78%
Cash surrender value	$ 39,746	$ 41,361
Life and Retirement | Life Insurance
Policyholder Account Balance [Roll Forward]
Policyholder contract deposits account balance, beginning of year	10,241	10,220	10,231	10,224
Deposits	407	414
Policy charges	(377)	(384)
Surrenders and withdrawals	(73)	(56)
Benefit payments	(79)	(49)
Net transfers from (to) separate account	5	(1)
Interest credited	121	88
Other	6	(16)
Other reconciling items	134	116
Policyholder contract deposits	$ 10,375	$ 10,336
Weighted average crediting rate	4.39%	4.24%
Cash surrender value	$ 9,042	$ 8,874
Life and Retirement | Institutional Markets
Policyholder Account Balance [Roll Forward]
Policyholder contract deposits account balance, beginning of year	14,337	12,294	13,649	11,734
Deposits	798	595
Policy charges	(17)	(17)
Surrenders and withdrawals	(31)	(403)
Benefit payments	(181)	(167)
Net transfers from (to) separate account	(27)	443
Interest credited	157	105
Other	(11)	4
Other reconciling items	33	74
Policyholder contract deposits	$ 14,370	$ 12,368
Weighted average crediting rate	4.59%	3.55%
Cash surrender value	$ 2,585	$ 2,545
Life and Retirement | Other
Policyholder Account Balance [Roll Forward]
Policyholder contract deposits account balance, beginning of year	3,272	3,516	$ 3,333	$ 3,587
Deposits	11	11
Policy charges	(15)	(16)
Surrenders and withdrawals	(21)	(20)
Benefit payments	(79)	(88)
Net transfers from (to) separate account	0	0
Interest credited	40	43
Other	3	(1)
Other reconciling items	(85)	(129)
Policyholder contract deposits	$ 3,187	$ 3,387
Weighted average crediting rate	4.98%	4.95%
Cash surrender value	$ 1,696	$ 1,781
Life and Retirement | Other Operations
Policyholder Account Balance [Roll Forward]
Other reconciling items	$ (85)	$ (129)