Deferred acquisition costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	$ 7,537
Balance – beginning of period	7,152
Amortization expense	(2,207)	$ (1,948)
Balance - end of period	7,537
Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(294)	(273)
Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(823)	(713)
Short-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,510	3,003
Balance - end of period	3,510	3,003
Long-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	4,027	3,293
Balance - end of period	4,027	3,293
Long-Duration Insurance, Other | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,411	2,651
Balance – beginning of period	3,185	2,514
Capitalizations	339	222
Amortization expense	(104)	(84)
Other (including foreign exchange)	(9)	(1)
Balance - end of period	3,411	2,651
Long-Duration Insurance, Other | Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	616	642
Balance - end of period	616	642
Term Life Insurance | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	413	349
Balance – beginning of period	402	324
Capitalizations	47	42
Amortization expense	(28)	(24)
Other (including foreign exchange)	(8)	7
Balance - end of period	413	349
Universal Life | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	688	644
Balance – beginning of period	674	639
Capitalizations	33	25
Amortization expense	(20)	(19)
Other (including foreign exchange)	1	(1)
Balance - end of period	688	644
Whole Life Insurance | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	608	424
Balance – beginning of period	534	392
Capitalizations	85	28
Amortization expense	(8)	(5)
Other (including foreign exchange)	(3)	9
Balance - end of period	608	424
Accident and Health Insurance Product Line [Member] | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	1,421	969
Balance – beginning of period	1,301	891
Capitalizations	158	123
Amortization expense	(41)	(30)
Other (including foreign exchange)	3	(15)
Balance - end of period	1,421	969
Insurance, Other | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	281	265
Balance – beginning of period	274	268
Capitalizations	16	4
Amortization expense	(7)	(6)
Other (including foreign exchange)	(2)	(1)
Balance - end of period	$ 281	$ 265