Future policy benefits (Rollforward) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Consolidation of Huatai Group			$ 1,850
Consolidation of Huatai Group			4,072
Deferred profit liability		$ 1,622	1,123
Net liability for future policy benefits, before reinsurance recoverable		16,003	13,109	$ 13,888
Less: Reinsurance recoverable on future policy benefits	[1]	292		280
Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		16,036	14,867
Beginning balance at original discount rate				16,693	$ 15,529
Effect of changes in cash flow assumptions				410	(735)
Effect of actual variances from expected experience				(112)	(109)
Adjusted beginning of period balance		16,991	14,685
Issuances		2,873	1,344
Interest accrual		563	529
Net premiums collected (1)	[2]	(2,167)	(1,516)
Other (including foreign exchange)		(140)	(587)
Ending balance at original discount rate		18,120	16,305
Effect of changes in discount rate assumptions		(56)	(628)
Balance – end of period		18,064	15,677
Balance – beginning of period		27,462	23,324
Beginning balance at original discount rate				28,303	24,456
Effect of changes in cash flow assumptions				387	(770)
Effect of actual variances from expected experience				(93)	(95)
Adjusted beginning of period balance		28,597	23,591
Issuances		2,873	1,344
Interest accrual		829	750
Benefits payments		(1,633)	(1,405)
Other (including foreign exchange)		(65)	(651)
Ending balance at original discount rate		30,601	27,701
Effect of changes in discount rate assumptions		455	(1,224)
Balance – end of period		31,056	26,477
Net liability for future policy benefits		12,992	10,800
Deferred profit liability		1,622	1,123
Net liability for future policy benefits, before reinsurance recoverable		14,614	11,923
Less: Reinsurance recoverable on future policy benefits		266	282
Net liability for future policy benefits, after reinsurance recoverable		$ 14,348	$ 11,641
Weighted average duration (years)		21 years 1 month 6 days	19 years 7 months 6 days
Other Segments
Liability for Future Policy Benefit, Activity [Line Items]
Net liability for future policy benefits, before reinsurance recoverable		$ 1,389	$ 1,186
Term Life Insurance | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		1,590	1,806
Beginning balance at original discount rate				1,992	1,867
Effect of changes in cash flow assumptions				(140)	36
Effect of actual variances from expected experience				6	(15)
Adjusted beginning of period balance		1,858	1,888
Consolidation of Huatai Group			3
Issuances		161	90
Interest accrual		45	45
Net premiums collected (1)	[2]	(183)	(127)
Other (including foreign exchange)		(10)	78
Ending balance at original discount rate		1,871	1,977
Effect of changes in discount rate assumptions		(287)	(69)
Balance – end of period		1,584	1,908
Balance – beginning of period		2,254	2,321
Beginning balance at original discount rate				2,749	2,447
Effect of changes in cash flow assumptions				(137)	32
Effect of actual variances from expected experience				13	(12)
Adjusted beginning of period balance		2,625	2,467
Consolidation of Huatai Group			17
Issuances		161	90
Interest accrual		59	54
Benefits payments		(173)	(120)
Other (including foreign exchange)		27	227
Ending balance at original discount rate		2,699	2,735
Effect of changes in discount rate assumptions		(390)	(149)
Balance – end of period		2,309	2,586
Net liability for future policy benefits		725	678
Deferred profit liability		276	244
Net liability for future policy benefits, before reinsurance recoverable		1,001	922
Less: Reinsurance recoverable on future policy benefits		109	111
Net liability for future policy benefits, after reinsurance recoverable		$ 892	$ 811
Weighted average duration (years)		10 years 2 months 12 days	10 years 2 months 12 days
Whole Life Insurance | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		$ 3,950	$ 2,308
Beginning balance at original discount rate				3,945	2,361
Effect of changes in cash flow assumptions				160	40
Effect of actual variances from expected experience				9	77
Adjusted beginning of period balance		4,114	2,478
Consolidation of Huatai Group			1,690
Issuances		942	223
Interest accrual		91	62
Net premiums collected (1)	[2]	(852)	(376)
Other (including foreign exchange)		14	(72)
Ending balance at original discount rate		4,309	4,005
Effect of changes in discount rate assumptions		94	(62)
Balance – end of period		4,403	3,943
Balance – beginning of period		10,063	5,696
Beginning balance at original discount rate				9,991	5,874
Effect of changes in cash flow assumptions				181	44
Effect of actual variances from expected experience				21	86
Adjusted beginning of period balance		10,193	6,004
Consolidation of Huatai Group			3,659
Issuances		942	223
Interest accrual		240	176
Benefits payments		(260)	(212)
Other (including foreign exchange)		55	30
Ending balance at original discount rate		11,170	9,880
Effect of changes in discount rate assumptions		739	(274)
Balance – end of period		11,909	9,606
Net liability for future policy benefits		7,506	5,663
Deferred profit liability		1,120	709
Net liability for future policy benefits, before reinsurance recoverable		8,626	6,372
Less: Reinsurance recoverable on future policy benefits		45	47
Net liability for future policy benefits, after reinsurance recoverable		$ 8,581	$ 6,325
Weighted average duration (years)		27 years 9 months 18 days	26 years 6 months
Accident and Health Insurance Product Line [Member] | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		$ 10,432	$ 10,711
Beginning balance at original discount rate				10,692	11,258
Effect of changes in cash flow assumptions				394	(813)
Effect of actual variances from expected experience				(126)	(170)
Adjusted beginning of period balance		10,960	10,275
Consolidation of Huatai Group			145
Issuances		1,717	1,026
Interest accrual		424	421
Net premiums collected (1)	[2]	(1,105)	(998)
Other (including foreign exchange)		(158)	(592)
Ending balance at original discount rate		11,838	10,277
Effect of changes in discount rate assumptions		136	(496)
Balance – end of period		11,974	9,781
Balance – beginning of period		14,650	15,038
Beginning balance at original discount rate				15,071	15,855
Effect of changes in cash flow assumptions				348	(849)
Effect of actual variances from expected experience				(127)	(168)
Adjusted beginning of period balance		15,292	14,838
Consolidation of Huatai Group			163
Issuances		1,717	1,026
Interest accrual		519	514
Benefits payments		(1,186)	(1,064)
Other (including foreign exchange)		(188)	(1,062)
Ending balance at original discount rate		16,154	14,415
Effect of changes in discount rate assumptions		65	(790)
Balance – end of period		16,219	13,625
Net liability for future policy benefits		4,245	3,844
Deferred profit liability		194	156
Net liability for future policy benefits, before reinsurance recoverable		4,439	4,000
Less: Reinsurance recoverable on future policy benefits		112	103
Net liability for future policy benefits, after reinsurance recoverable		$ 4,327	$ 3,897
Weighted average duration (years)		9 years 9 months 18 days	10 years 3 months 18 days
Insurance, Other | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		$ 64	$ 42
Beginning balance at original discount rate				64	43
Effect of changes in cash flow assumptions				(4)	2
Effect of actual variances from expected experience				(1)	(1)
Adjusted beginning of period balance		59	44
Consolidation of Huatai Group			12
Issuances		53	5
Interest accrual		3	1
Net premiums collected (1)	[2]	(27)	(15)
Other (including foreign exchange)		14	(1)
Ending balance at original discount rate		102	46
Effect of changes in discount rate assumptions		1	(1)
Balance – end of period		103	45
Balance – beginning of period		495	269
Beginning balance at original discount rate				492	280
Effect of changes in cash flow assumptions				(5)	3
Effect of actual variances from expected experience				$ 0	$ (1)
Adjusted beginning of period balance		487	282
Consolidation of Huatai Group			233
Issuances		53	5
Interest accrual		11	6
Benefits payments		(14)	(9)
Other (including foreign exchange)		41	154
Ending balance at original discount rate		578	671
Effect of changes in discount rate assumptions		41	(11)
Balance – end of period		619	660
Net liability for future policy benefits		516	615
Deferred profit liability		32	14
Net liability for future policy benefits, before reinsurance recoverable		548	629
Less: Reinsurance recoverable on future policy benefits		0	21
Net liability for future policy benefits, after reinsurance recoverable		$ 548	$ 608
Weighted average duration (years)		17 years 7 months 6 days	15 years 1 month 6 days

[1] Net of valuation allowance for uncollectible reinsurance.

[2] Net premiums collected represent the portion of gross premiums collected from policyholders that is used to fund expected benefit.