Deferred acquisition costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	$ 8,249	$ 6,856	$ 8,249	$ 6,856
Balance – beginning of period			7,152
Amortization expense	(2,324)	(2,178)	(6,757)	(6,142)
Balance – end of period	8,249	6,856	8,249	6,856
Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(291)	(279)	(885)	(829)
Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Amortization expense	(852)	(827)	(2,517)	(2,286)
Short-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,735	3,283	3,735	3,283
Balance – end of period	3,735	3,283	3,735	3,283
Long-Duration Insurance, Other
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	4,514	3,573	4,514	3,573
Balance – end of period	4,514	3,573	4,514	3,573
Long-Duration Insurance, Other | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	3,899	2,952	3,899	2,952
Balance – beginning of period			3,185	2,514
Capitalizations			1,054	742
Amortization expense			(328)	(266)
Other (including foreign exchange)			(12)	(38)
Balance – end of period	3,899	2,952	3,899	2,952
Long-Duration Insurance, Other | Overseas General Insurance [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	615	621	615	621
Balance – end of period	615	621	615	621
Term Life Insurance | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	461	377	461	377
Balance – beginning of period			402	324
Capitalizations			149	131
Amortization expense			(89)	(76)
Other (including foreign exchange)			(1)	(2)
Balance – end of period	461	377	461	377
Universal Life | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	721	651	721	651
Balance – beginning of period			674	639
Capitalizations			109	85
Amortization expense			(60)	(55)
Other (including foreign exchange)			(2)	(18)
Balance – end of period	721	651	721	651
Whole Life Insurance | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	785	480	785	480
Balance – beginning of period			534	392
Capitalizations			276	103
Amortization expense			(27)	(18)
Other (including foreign exchange)			2	3
Balance – end of period	785	480	785	480
Accident and Health Insurance Product Line [Member] | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	1,628	1,170	1,628	1,170
Balance – beginning of period			1,301	891
Capitalizations			467	396
Amortization expense			(132)	(98)
Other (including foreign exchange)			(8)	(19)
Balance – end of period	1,628	1,170	1,628	1,170
Insurance, Other | Segment Life [Member]
Deferred Policy Acquisition Cost [Line Items]
Deferred Policy Acquisition Cost	304	274	304	274
Balance – beginning of period			274	268
Capitalizations			53	27
Amortization expense			(20)	(19)
Other (including foreign exchange)			(3)	(2)
Balance – end of period	$ 304	$ 274	$ 304	$ 274