Deferred acquisition costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	$ 8,358	$ 7,152
Balance – beginning of period	7,152
Amortization expense	(9,102)	(8,259)	$ (7,339)
Balance - end of period	8,358	7,152
Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(1,202)	(1,089)	(785)
Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(3,410)	(3,113)	(2,818)
Short-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,687	3,346
Balance – beginning of period	3,346
Balance - end of period	3,687	3,346
Long-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	4,671	3,806
Balance – beginning of period	3,806
Balance - end of period	4,671	3,806
Long-Duration Insurance, Other | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	4,066	3,185	2,514
Balance – beginning of period	3,185	2,514
Capitalizations	1,456	1,064
Amortization expense	(448)	(369)
Other (including foreign exchange)	(127)	(24)
Balance - end of period	4,066	3,185	2,514
Long-Duration Insurance, Other | Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	605	621
Balance – beginning of period	621
Balance - end of period	605	621
Term Life Insurance | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	469	402	324
Balance – beginning of period	402	324
Capitalizations	201	176
Amortization expense	(121)	(100)
Other (including foreign exchange)	(13)	2
Balance - end of period	469	402	324
Universal Life | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	722	674	639
Balance – beginning of period	674	639
Capitalizations	156	129
Amortization expense	(81)	(80)
Other (including foreign exchange)	(27)	(14)
Balance - end of period	722	674	639
Whole Life Insurance | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	870	534	392
Balance – beginning of period	534	392
Capitalizations	387	159
Amortization expense	(37)	(23)
Other (including foreign exchange)	(14)	6
Balance - end of period	870	534	392
Accident and Health [Member] | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	1,681	1,301	891
Balance – beginning of period	1,301	891
Capitalizations	630	564
Amortization expense	(182)	(137)
Other (including foreign exchange)	(68)	(17)
Balance - end of period	1,681	1,301	891
Insurance, Other [Member] | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	324	274	268
Balance – beginning of period	274	268
Capitalizations	82	36
Amortization expense	(27)	(29)
Other (including foreign exchange)	(5)	(1)
Balance - end of period	$ 324	$ 274	$ 268