Deferred acquisition costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	$ 6,666		$ 6,666
Balance – beginning of period			6,031
Amortization expense	(2,016)	$ (1,726)	(3,964)	$ (3,445)
Balance - end of period	6,666		6,666
Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(277)	(138)	(550)	(271)
Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(746)	(697)	(1,459)	(1,376)
Short-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,201	2,876	3,201	2,876
Balance - end of period	3,201	2,876	3,201	2,876
Long-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,465	2,929	3,465	2,929
Balance - end of period	3,465	2,929	3,465	2,929
Long-Duration Insurance, Other | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	2,814	2,242	2,814	2,242
Balance – beginning of period			2,514	2,204
Capitalizations			444	228
Amortization expense			(171)	(139)
Other (including foreign exchange)			27	(51)
Balance - end of period	2,814	2,242	2,814	2,242
Long-Duration Insurance, Other | Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	651	687	651	687
Balance - end of period	651	687	651	687
Term Life Insurance | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	356	283	356	283
Balance – beginning of period			320	246
Capitalizations			75	72
Amortization expense			(49)	(36)
Other (including foreign exchange)			10	1
Balance - end of period	356	283	356	283
Universal Life | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	803	765	803	765
Balance – beginning of period			776	771
Capitalizations			54	58
Amortization expense			(38)	(37)
Other (including foreign exchange)			11	(27)
Balance - end of period	803	765	803	765
Whole Life Insurance | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	456	336	456	336
Balance – beginning of period			395	334
Capitalizations			62	19
Amortization expense			(11)	(9)
Other (including foreign exchange)			10	(8)
Balance - end of period	456	336	456	336
Accident and Health Insurance Product Line [Member] | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	1,081	740	1,081	740
Balance – beginning of period			902	745
Capitalizations			246	50
Amortization expense			(63)	(47)
Other (including foreign exchange)			(4)	(8)
Balance - end of period	1,081	740	1,081	740
Insurance, Other | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	118	118	118	118
Balance – beginning of period			121	108
Capitalizations			7	29
Amortization expense			(10)	(10)
Other (including foreign exchange)			0	(9)
Balance - end of period	$ 118	$ 118	$ 118	$ 118