Deferred acquisition costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	$ 7,812	$ 6,666	$ 7,812	$ 6,666
Balance – beginning of period			7,152
Amortization expense	(2,226)	(2,016)	(4,433)	(3,964)
Balance - end of period	7,812	6,666	7,812	6,666
Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(300)	(277)	(594)	(550)
Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(842)	(746)	(1,665)	(1,459)
Short-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,646	3,187	3,646	3,187
Balance - end of period	3,646	3,187	3,646	3,187
Long-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	4,166	3,479	4,166	3,479
Balance - end of period	4,166	3,479	4,166	3,479
Long-Duration Insurance, Other | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,574	2,828	3,574	2,828
Balance – beginning of period			3,185	2,514
Capitalizations			685	458
Amortization expense			(214)	(173)
Other (including foreign exchange)			(82)	29
Balance - end of period	3,574	2,828	3,574	2,828
Long-Duration Insurance, Other | Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	592	651	592	651
Balance - end of period	592	651	592	651
Term Life Insurance | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	436	370	436	370
Balance – beginning of period			402	324
Capitalizations			98	84
Amortization expense			(58)	(50)
Other (including foreign exchange)			(6)	12
Balance - end of period	436	370	436	370
Universal Life | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	680	665	680	665
Balance – beginning of period			674	639
Capitalizations			70	54
Amortization expense			(39)	(37)
Other (including foreign exchange)			(25)	9
Balance - end of period	680	665	680	665
Whole Life Insurance | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	673	453	673	453
Balance – beginning of period			534	392
Capitalizations			170	62
Amortization expense			(17)	(11)
Other (including foreign exchange)			(14)	10
Balance - end of period	673	453	673	453
Accident and Health Insurance Product Line [Member] | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	1,496	1,076	1,496	1,076
Balance – beginning of period			1,301	891
Capitalizations			311	249
Amortization expense			(86)	(62)
Other (including foreign exchange)			(30)	(2)
Balance - end of period	1,496	1,076	1,496	1,076
Insurance, Other | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	289	264	289	264
Balance – beginning of period			274	268
Capitalizations			36	9
Amortization expense			(14)	(13)
Other (including foreign exchange)			(7)	0
Balance - end of period	$ 289	$ 264	$ 289	$ 264