Insurance Liabilities - Balances of changes in liability for future policy benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2021	Dec. 31, 2020
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of year	$ 14,574
Effect of changes in discount rate assumptions (AOCI)	(2,200)
Beginning balance at original discount rate	16,774
Effect of changes in cash flow assumptions		$ 53
Effect of actual variances from expected experience		66
Adjusted beginning of year balance	16,893
Issuances	1,399
Interest accrual	526
Net premium collected	(1,865)
Foreign exchange impact	251
Other	2
Ending balance at original discount rate	17,206	16,774
Effect of changes in discount rate assumptions (AOCI)	(1,865)	(2,200)
Reclassified to Liabilities held for sale	(4,287)
Balance, end of period	11,054	14,574
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	57,886
Effect of changes in discount rate assumptions (AOCI)	(7,672)
Beginning balance at original discount rate	65,558
Adjustments		125
Effect of actual variances from expected experience		112
Adjusted beginning of year balance	65,795
Issuances	6,930
Interest accrual	2,716
Benefit payments	(4,941)
Foreign exchange impact	677
Other	(14)
Ending balance at original discount rate	71,163	65,558
Effect of changes in discount rate assumptions (AOCI)	(5,658)	(7,672)
Reclassified to Liabilities held for sale	(5,119)
Ending balance	60,386	57,886
Net liability for future policy benefits, end of period	49,332
Liability for future policy benefits for certain participating contracts	1,313
Liability for universal life policies with secondary guarantees and similar features	3,786
Deferred profit liability	2,512
Other reconciling items	1,633
Future policy benefits for life and accident and health insurance contracts	58,576	51,914		$ 67,364
Less: Reinsurance recoverable:	(23,571)
Net liability for future policy benefits after reinsurance recoverable	35,005
General Insurance
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of year	1,929
Effect of changes in discount rate assumptions (AOCI)	(262)
Beginning balance at original discount rate	2,191
Effect of changes in cash flow assumptions		(2)
Effect of actual variances from expected experience		(16)
Adjusted beginning of year balance	2,173
Issuances	122
Interest accrual	43
Net premium collected	(283)
Foreign exchange impact	(14)
Other	0
Ending balance at original discount rate	2,041	2,191
Effect of changes in discount rate assumptions (AOCI)	(339)	(262)
Reclassified to Liabilities held for sale	0
Balance, end of period	1,702	1,929
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	2,380
Effect of changes in discount rate assumptions (AOCI)	(362)
Beginning balance at original discount rate	2,742
Adjustments		(13)
Effect of actual variances from expected experience		(18)
Adjusted beginning of year balance	2,711
Issuances	130
Interest accrual	52
Benefit payments	(276)
Foreign exchange impact	(27)
Other	0
Ending balance at original discount rate	2,590	2,742
Effect of changes in discount rate assumptions (AOCI)	(441)	(362)
Reclassified to Liabilities held for sale	0
Ending balance	2,149	2,380
Net liability for future policy benefits, end of period	$ 447
Weighted average liability duration of the liability for future policy benefits (in years)	9 years 3 months 18 days
Life and Retirement
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of year	$ 12,645	15,643	$ 15,299
Effect of changes in discount rate assumptions (AOCI)	(1,938)	856	1,623
Beginning balance at original discount rate	14,583	14,787	13,676
Effect of changes in cash flow assumptions			123		$ 92
Effect of actual variances from expected experience			(72)		385
Adjusted beginning of year balance		14,838	14,153
Issuances		1,358	1,727
Interest accrual		445	446
Net premium collected		(1,541)	(1,493)
Foreign exchange impact		(517)	(46)
Other		0	0
Ending balance at original discount rate		14,583	14,787
Effect of changes in discount rate assumptions (AOCI)		(1,938)	856
Balance, end of period		12,645	15,643
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	55,506	70,643	71,668
Effect of changes in discount rate assumptions (AOCI)	(7,310)	9,401	14,086
Beginning balance at original discount rate	62,816	61,242	57,582
Adjustments			134		110
Effect of actual variances from expected experience			(122)		289
Adjusted beginning of year balance		61,254	57,981
Issuances		4,393	5,287
Interest accrual		2,620	2,393
Benefit payments		(4,203)	(4,336)
Foreign exchange impact		(996)	(63)
Other		(252)	(20)
Ending balance at original discount rate		62,816	61,242
Effect of changes in discount rate assumptions (AOCI)		(7,310)	9,401
Ending balance		55,506	70,643
Net liability for future policy benefits, end of period		42,861	55,000
Liability for future policy benefits for certain participating contracts		1,352	1,397
Liability for universal life policies with secondary guarantees and similar features		3,355	5,007
Deferred profit liability		2,303	2,236
Other reconciling items		2,043	2,759
Future policy benefits for life and accident and health insurance contracts		51,914	66,399
Less: Reinsurance recoverable:		(24,078)	(32,586)
Net liability for future policy benefits after reinsurance recoverable		27,836	33,813
Life and Retirement | Individual Retirement
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of year	0	0	0
Effect of changes in discount rate assumptions (AOCI)	0	0	0
Beginning balance at original discount rate	0	0	0
Effect of changes in cash flow assumptions		0	0		0
Effect of actual variances from expected experience		0	0		0
Adjusted beginning of year balance	0	0	0
Issuances	0	0	0
Interest accrual	0	0	0
Net premium collected	0	0	0
Foreign exchange impact	0	0	0
Other	0	0	0
Ending balance at original discount rate	0	0	0
Effect of changes in discount rate assumptions (AOCI)	0	0	0
Reclassified to Liabilities held for sale	0
Balance, end of period	0	0	0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	1,223	1,373	1,322
Effect of changes in discount rate assumptions (AOCI)	(167)	95	156
Beginning balance at original discount rate	1,390	1,278	1,166
Adjustments		0	0		0
Effect of actual variances from expected experience		(5)	(30)		1
Adjusted beginning of year balance	1,385	1,248	1,167
Issuances	173	216	172
Interest accrual	55	42	41
Benefit payments	(128)	(116)	(101)
Foreign exchange impact	0	0	0
Other	0	0	(1)
Ending balance at original discount rate	1,485	1,390	1,278
Effect of changes in discount rate assumptions (AOCI)	(132)	(167)	95
Reclassified to Liabilities held for sale	0
Ending balance	1,353	1,223	1,373
Net liability for future policy benefits, end of period	$ 1,353	$ 1,223	$ 1,373
Weighted average liability duration of the liability for future policy benefits (in years)	7 years 9 months 18 days	7 years 7 months 6 days	8 years 7 months 6 days
Life and Retirement | Group Retirement
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of year	$ 0	$ 0	$ 0
Effect of changes in discount rate assumptions (AOCI)	0	0	0
Beginning balance at original discount rate	0	0	0
Effect of changes in cash flow assumptions		0	0		0
Effect of actual variances from expected experience		0	0		0
Adjusted beginning of year balance	0	0	0
Issuances	0	0	0
Interest accrual	0	0	0
Net premium collected	0	0	0
Foreign exchange impact	0	0	0
Other	0	0	0
Ending balance at original discount rate	0	0	0
Effect of changes in discount rate assumptions (AOCI)	0	0	0
Reclassified to Liabilities held for sale	0
Balance, end of period	0	0	0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	211	264	279
Effect of changes in discount rate assumptions (AOCI)	(2)	46	63
Beginning balance at original discount rate	213	218	216
Adjustments		0	0		0
Effect of actual variances from expected experience		(2)	(2)		(1)
Adjusted beginning of year balance	211	216	215
Issuances	18	12	21
Interest accrual	11	10	11
Benefit payments	(26)	(26)	(28)
Foreign exchange impact	0	0	0
Other	0	1	(1)
Ending balance at original discount rate	214	213	218
Effect of changes in discount rate assumptions (AOCI)	3	(2)	46
Reclassified to Liabilities held for sale	0
Ending balance	217	211	264
Net liability for future policy benefits, end of period	$ 217	$ 211	$ 264
Weighted average liability duration of the liability for future policy benefits (in years)	6 years 9 months 18 days	6 years 10 months 24 days	7 years 9 months 18 days
Life and Retirement | Life Insurance
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of year	$ 11,654	$ 14,369	$ 13,793
Effect of changes in discount rate assumptions (AOCI)	(1,872)	706	1,374
Beginning balance at original discount rate	13,526	13,663	12,419
Effect of changes in cash flow assumptions		34	123		164
Effect of actual variances from expected experience		62	(79)		371
Adjusted beginning of year balance	13,622	13,707	12,954
Issuances	1,277	1,358	1,727
Interest accrual	437	397	392
Net premium collected	(1,464)	(1,418)	(1,364)
Foreign exchange impact	265	(517)	(46)
Other	11	(1)	0
Ending balance at original discount rate	14,148	13,526	13,663
Effect of changes in discount rate assumptions (AOCI)	(1,482)	(1,872)	706
Reclassified to Liabilities held for sale	(4,287)
Balance, end of period	8,379	11,654	14,369
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	21,179	27,442	27,918
Effect of changes in discount rate assumptions (AOCI)	(3,424)	2,717	4,351
Beginning balance at original discount rate	24,603	24,725	23,567
Adjustments		62	140		193
Effect of actual variances from expected experience		122	(94)		413
Adjusted beginning of year balance	24,787	24,771	24,173
Issuances	1,266	1,374	1,713
Interest accrual	908	876	876
Benefit payments	(1,921)	(1,757)	(1,981)
Foreign exchange impact	345	(657)	(60)
Other	10	(4)	4
Ending balance at original discount rate	25,395	24,603	24,725
Effect of changes in discount rate assumptions (AOCI)	(2,745)	(3,424)	2,717
Reclassified to Liabilities held for sale	(5,119)
Ending balance	17,531	21,179	27,442
Net liability for future policy benefits, end of period	$ 9,152	$ 9,525	$ 13,073
Weighted average liability duration of the liability for future policy benefits (in years)	12 years 9 months 18 days	12 years 2 months 12 days	14 years 4 months 24 days
Life and Retirement | Institutional Markets
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of year	$ 0	$ 0	$ 0
Effect of changes in discount rate assumptions (AOCI)	0	0	0
Beginning balance at original discount rate	0	0	0
Effect of changes in cash flow assumptions		0	0		0
Effect of actual variances from expected experience		0	0		0
Adjusted beginning of year balance	0	0	0
Issuances	0	0	0
Interest accrual	0	0	0
Net premium collected	0	0	0
Foreign exchange impact	0	0	0
Other	0	0	0
Ending balance at original discount rate	0	0	0
Effect of changes in discount rate assumptions (AOCI)	0	0	0
Reclassified to Liabilities held for sale	0
Balance, end of period	0	0	0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	12,464	13,890	11,630
Effect of changes in discount rate assumptions (AOCI)	(2,634)	870	1,654
Beginning balance at original discount rate	15,098	13,020	9,976
Adjustments		0	(6)		0
Effect of actual variances from expected experience		15	3		(3)
Adjusted beginning of year balance	15,113	13,017	9,973
Issuances	5,339	2,782	3,366
Interest accrual	664	459	380
Benefit payments	(1,087)	(821)	(696)
Foreign exchange impact	359	(339)	(3)
Other	0	0	0
Ending balance at original discount rate	20,388	15,098	13,020
Effect of changes in discount rate assumptions (AOCI)	(1,906)	(2,634)	870
Reclassified to Liabilities held for sale	0
Ending balance	18,482	12,464	13,890
Net liability for future policy benefits, end of period	$ 18,482	$ 12,464	$ 13,890
Weighted average liability duration of the liability for future policy benefits (in years)	12 years 1 month 6 days	10 years 9 months 18 days	13 years
Life and Retirement | Other
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of year	$ 991	$ 1,274	$ 1,506
Effect of changes in discount rate assumptions (AOCI)	(66)	150	249
Beginning balance at original discount rate	1,057	1,124	1,257
Effect of changes in cash flow assumptions		21	0		(72)
Effect of actual variances from expected experience		20	7		14
Adjusted beginning of year balance	1,098	1,131	1,199
Issuances	0	0	0
Interest accrual	46	48	54
Net premium collected	(118)	(123)	(129)
Foreign exchange impact	0	0	0
Other	(9)	1	0
Ending balance at original discount rate	1,017	1,057	1,124
Effect of changes in discount rate assumptions (AOCI)	(44)	(66)	150
Reclassified to Liabilities held for sale	0
Balance, end of period	973	991	1,274
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	20,429	27,674	30,519
Effect of changes in discount rate assumptions (AOCI)	(1,083)	5,673	7,862
Beginning balance at original discount rate	21,512	22,001	22,657
Adjustments		76	0		(83)
Effect of actual variances from expected experience		0	1		$ (121)
Adjusted beginning of year balance	21,588	22,002	22,453
Issuances	4	9	15
Interest accrual	1,026	1,233	1,085
Benefit payments	(1,503)	(1,483)	(1,530)
Foreign exchange impact	0	0	0
Other	(24)	(249)	(22)
Ending balance at original discount rate	21,091	21,512	22,001
Effect of changes in discount rate assumptions (AOCI)	(437)	(1,083)	5,673
Reclassified to Liabilities held for sale	0
Ending balance	20,654	20,429	27,674
Net liability for future policy benefits, end of period	$ 19,681	$ 19,438	$ 26,400
Weighted average liability duration of the liability for future policy benefits (in years)	11 years 6 months	11 years 4 months 24 days	13 years 8 months 12 days