Deferred acquisition costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	$ 7,152	$ 6,031
Balance – beginning of period	6,031
Amortization expense	(8,259)	(7,339)	$ (6,758)
Balance - end of period	7,152	6,031
Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(1,089)	(785)	(552)
Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(3,113)	(2,818)	(2,799)
Short-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,346	2,877	2,718
Balance – beginning of period	2,877	2,718
Balance - end of period	3,346	2,877	2,718
Long-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,806	3,154	2,970
Balance – beginning of period	3,154	2,970
Balance - end of period	3,806	3,154	2,970
Long-Duration Insurance, Other | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,185	2,514	2,204
Balance – beginning of period	2,514	2,204	1,934
Capitalizations	1,064	667	542
Amortization expense	(369)	(287)	(250)
Other (including foreign exchange)	(24)	(70)	(22)
Balance - end of period	3,185	2,514	2,204
Long-Duration Insurance, Other | Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	621	640	766
Balance – beginning of period	640	766
Balance - end of period	621	640	766
Term Life Insurance | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	402	324	250
Balance – beginning of period	324	250	125
Capitalizations	176	147	178
Amortization expense	(100)	(81)	(47)
Other (including foreign exchange)	2	8	(6)
Balance - end of period	402	324	250
Universal Life | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	674	639	631
Balance – beginning of period	639	631	557
Capitalizations	129	118	143
Amortization expense	(80)	(64)	(61)
Other (including foreign exchange)	(14)	(46)	(8)
Balance - end of period	674	639	631
Whole Life Insurance | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	534	392	330
Balance – beginning of period	392	330	299
Capitalizations	159	86	52
Amortization expense	(23)	(18)	(18)
Other (including foreign exchange)	6	(6)	(3)
Balance - end of period	534	392	330
Accident and Health [Member] | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	1,301	891	730
Balance – beginning of period	891	730	733
Capitalizations	564	268	98
Amortization expense	(137)	(93)	(98)
Other (including foreign exchange)	(17)	(14)	(3)
Balance - end of period	1,301	891	730
Insurance, Other [Member] | Life Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	274	268	263
Balance – beginning of period	268	263	220
Capitalizations	36	48	71
Amortization expense	(29)	(31)	(26)
Other (including foreign exchange)	(1)	(12)	(2)
Balance - end of period	$ 274	$ 268	$ 263