Future policy benefits (Rollforward) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2021
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		$ 13,024	$ 4,313
Beginning balance at original discount rate				$ 13,685	$ 3,991
Effect of changes in cash flow assumptions				(756)	(2)
Effect of actual variances from expected experience				(46)	(112)
Adjusted beginning of period balance		12,883	3,877
Issuances		786	206
Interest accrual		299	124
Net premiums collected (1)	[1]	(921)	(263)
Other (including foreign exchange)		(157)	(60)
Ending balance at original discount rate		13,204	3,884
Effect of changes in discount rate assumptions		(424)	(155)
Balance – end of period		12,780	3,729
Balance – beginning of period		21,920	10,775
Beginning balance at original discount rate				23,052	9,402
Effect of changes in cash flow assumptions				(762)	4
Effect of actual variances from expected experience				(36)	(112)
Adjusted beginning of period balance		22,254	9,294
Issuances		785	209
Interest accrual		440	209
Benefits payments		(927)	(306)
Other (including foreign exchange)		299	158
Ending balance at original discount rate		22,851	9,248
Effect of changes in discount rate assumptions		(784)	(203)
Balance – end of period		22,067	9,045
Net liability for future policy benefits		10,038	6,064
Deferred profit liability		1,026	692
Net liability for future policy benefits, per consolidated balance sheet		11,064	6,756	10,476		$ 7,652
Less: Reinsurance recoverable on future policy benefits		315	242
Net liability for future policy benefits, after reinsurance recoverable		$ 10,749	$ 6,514
Weighted average duration (years)		16 years 4 months 24 days	14 years 1 month 6 days
Term Life Insurance | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		$ 818	$ 422
Beginning balance at original discount rate				879	397
Effect of changes in cash flow assumptions				15	0
Effect of actual variances from expected experience				(4)	(27)
Adjusted beginning of period balance		890	370
Issuances		62	66
Interest accrual		37	31
Net premiums collected (1)	[1]	(86)	(51)
Other (including foreign exchange)		(17)	(12)
Ending balance at original discount rate		920	404
Effect of changes in discount rate assumptions		(56)	(24)
Balance – end of period		864	380
Balance – beginning of period		1,427	921
Beginning balance at original discount rate				1,555	858
Effect of changes in cash flow assumptions				17	(5)
Effect of actual variances from expected experience				(3)	(25)
Adjusted beginning of period balance		1,569	828
Issuances		62	69
Interest accrual		43	35
Benefits payments		(84)	(44)
Other (including foreign exchange)		71	32
Ending balance at original discount rate		1,661	856
Effect of changes in discount rate assumptions		(130)	(68)
Balance – end of period		1,531	788
Net liability for future policy benefits		667	408
Deferred profit liability		225	165
Net liability for future policy benefits, per consolidated balance sheet		892	573			454
Less: Reinsurance recoverable on future policy benefits		110	108
Net liability for future policy benefits, after reinsurance recoverable		$ 782	$ 465
Weighted average duration (years)		9 years 3 months 18 days	9 years 3 months 18 days
Whole Life Insurance | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		$ 2,301	$ 1,341
Beginning balance at original discount rate				2,354	1,243
Effect of changes in cash flow assumptions				(1)	(2)
Effect of actual variances from expected experience				(7)	(11)
Adjusted beginning of period balance		2,346	1,230
Issuances		157	71
Interest accrual		35	21
Net premiums collected (1)	[1]	(171)	(80)
Other (including foreign exchange)		(23)	(30)
Ending balance at original discount rate		2,390	1,212
Effect of changes in discount rate assumptions		(21)	(27)
Balance – end of period		2,369	1,185
Balance – beginning of period		6,048	4,785
Beginning balance at original discount rate				6,225	3,833
Effect of changes in cash flow assumptions				(1)	(2)
Effect of actual variances from expected experience				(3)	(9)
Adjusted beginning of period balance		6,221	3,822
Issuances		158	71
Interest accrual		105	74
Benefits payments		(130)	(95)
Other (including foreign exchange)		400	77
Ending balance at original discount rate		6,754	3,795
Effect of changes in discount rate assumptions		(76)	76
Balance – end of period		6,678	3,871
Net liability for future policy benefits		4,309	2,686
Deferred profit liability		638	415
Net liability for future policy benefits, per consolidated balance sheet		4,947	3,101			3,767
Less: Reinsurance recoverable on future policy benefits		41	33
Net liability for future policy benefits, after reinsurance recoverable		$ 4,906	$ 3,068
Weighted average duration (years)		25 years	19 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		$ 9,863	$ 2,520
Beginning balance at original discount rate				10,409	2,323
Effect of changes in cash flow assumptions				(771)	0
Effect of actual variances from expected experience				(35)	(75)
Adjusted beginning of period balance		9,603	2,248
Issuances		564	67
Interest accrual		226	72
Net premiums collected (1)	[1]	(654)	(127)
Other (including foreign exchange)		(118)	(17)
Ending balance at original discount rate		9,857	2,243
Effect of changes in discount rate assumptions		(347)	(104)
Balance – end of period		9,510	2,139
Balance – beginning of period		14,206	4,939
Beginning balance at original discount rate				15,022	4,589
Effect of changes in cash flow assumptions				(780)	0
Effect of actual variances from expected experience				(30)	(79)
Adjusted beginning of period balance		14,212	4,510
Issuances		562	67
Interest accrual		289	100
Benefits payments		(708)	(167)
Other (including foreign exchange)		(178)	49
Ending balance at original discount rate		14,177	4,461
Effect of changes in discount rate assumptions		(574)	(204)
Balance – end of period		13,603	4,257
Net liability for future policy benefits		4,093	2,118
Deferred profit liability		149	104
Net liability for future policy benefits, per consolidated balance sheet		4,242	2,222			2,569
Less: Reinsurance recoverable on future policy benefits		126	58
Net liability for future policy benefits, after reinsurance recoverable		$ 4,116	$ 2,164
Weighted average duration (years)		10 years 7 months 6 days	10 years 3 months 18 days
Accident and Health Insurance Product Line [Member] | Overseas General Insurance [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Net liability for future policy benefits		$ 751	$ 748
Deferred profit liability		0	0
Net liability for future policy benefits, per consolidated balance sheet		751	748			773
Less: Reinsurance recoverable on future policy benefits		38	43
Net liability for future policy benefits, after reinsurance recoverable		$ 713	$ 705
Weighted average duration (years)		4 years 9 months 18 days	5 years 2 months 12 days
Insurance, Other | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		$ 42	$ 30
Beginning balance at original discount rate				43	28
Effect of changes in cash flow assumptions				1	0
Effect of actual variances from expected experience				0	1
Adjusted beginning of period balance		44	29
Issuances		3	2
Interest accrual		1	0
Net premiums collected (1)	[1]	(10)	(5)
Other (including foreign exchange)		1	(1)
Ending balance at original discount rate		37	25
Effect of changes in discount rate assumptions		0	0
Balance – end of period		37	25
Balance – beginning of period		239	130
Beginning balance at original discount rate				250	122
Effect of changes in cash flow assumptions				2	11
Effect of actual variances from expected experience				$ 0	$ 1
Adjusted beginning of period balance		252	134
Issuances		3	2
Interest accrual		3	0
Benefits payments		(5)	0
Other (including foreign exchange)		6	0
Ending balance at original discount rate		259	136
Effect of changes in discount rate assumptions		(4)	(7)
Balance – end of period		255	129
Net liability for future policy benefits		218	104
Deferred profit liability		14	8
Net liability for future policy benefits, per consolidated balance sheet		232	112			$ 89
Less: Reinsurance recoverable on future policy benefits		0	0
Net liability for future policy benefits, after reinsurance recoverable		$ 232	$ 112
Weighted average duration (years)		14 years	27 years 6 months

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