Deferred acquisition costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	$ 6,856		$ 6,856
Balance – beginning of period			6,031
Amortization expense	(2,178)	$ (1,970)	(6,142)	$ (5,415)
Balance - end of period	6,856		6,856
Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(279)	(266)	(829)	(537)
Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(827)	(720)	(2,286)	(2,096)
Short-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,283	2,809	3,283	2,809
Balance - end of period	3,283	2,809	3,283	2,809
Long-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,573	2,979	3,573	2,979
Balance - end of period	3,573	2,979	3,573	2,979
Long-Duration Insurance, Other | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	2,952	2,346	2,952	2,346
Balance – beginning of period			2,514	2,204
Capitalizations			722	457
Amortization expense			(262)	(213)
Other (including foreign exchange)			(22)	(102)
Balance - end of period	2,952	2,346	2,952	2,346
Long-Duration Insurance, Other | Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	621	633	621	633
Balance - end of period	621	633	621	633
Term Life Insurance | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	372	299	372	299
Balance – beginning of period			320	246
Capitalizations			118	111
Amortization expense			(74)	(56)
Other (including foreign exchange)			8	(2)
Balance - end of period	372	299	372	299
Universal Life | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	784	761	784	761
Balance – beginning of period			776	771
Capitalizations			85	95
Amortization expense			(57)	(55)
Other (including foreign exchange)			(20)	(50)
Balance - end of period	784	761	784	761
Whole Life Insurance | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	488	350	488	350
Balance – beginning of period			395	334
Capitalizations			102	46
Amortization expense			(16)	(14)
Other (including foreign exchange)			7	(16)
Balance - end of period	488	350	488	350
Accident and Health Insurance Product Line [Member] | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	1,181	819	1,181	819
Balance – beginning of period			902	745
Capitalizations			392	166
Amortization expense			(100)	(72)
Other (including foreign exchange)			(13)	(20)
Balance - end of period	1,181	819	1,181	819
Insurance, Other | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	127	117	127	117
Balance – beginning of period			121	108
Capitalizations			25	39
Amortization expense			(15)	(16)
Other (including foreign exchange)			(4)	(14)
Balance - end of period	$ 127	$ 117	$ 127	$ 117