Shareholders' equity AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	$ 50,519	$ 58,328
Other Comprehensive Income (Loss), before Tax	3,678	(10,076)	$ (2,507)
Other Comprehensive Income (Loss), Tax	317	(965)	(366)
Other Comprehensive Income (Loss), Net of Tax	3,361	(9,111)	(2,141)
Balance – end of year, net of tax	59,507	50,519	58,328
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	(7,279)	2,256	4,673
Balance – end of year, net of tax	(4,177)	(7,279)	2,256
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	2,948	(11,627)	(2,935)
Total net realized gains (losses) reclassified from AOCI	500	1,049	(3)
Other Comprehensive Income (Loss), before Tax	3,448	(10,578)	(2,938)
Other Comprehensive Income (Loss), Tax	328	(1,043)	(521)
Other Comprehensive Income (Loss), Net of Tax	3,120	(9,535)	(2,417)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	18	0	0
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	(66)	0	0
Balance – end of year, net of tax	(13)	(66)	0
Accumulated Defined Benefit Plans Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	225	240	(167)
Balance – end of year, net of tax	297	225	240
AOCI, Liability for Future Policy Benefit, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	(75)	(1,399)	0
Balance – end of year, net of tax	51	(75)	(1,399)
AOCI, Liability for Future Policy Benefit, Parent | Cumulative Effect, Period of Adoption, Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	0	0	(1,725)
Balance – end of year, net of tax		0	0
AOCI, Liability for Future Policy Benefit, Parent | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	(75)	(1,399)	(1,725)
Balance – end of year, net of tax		(75)	(1,399)
AOCI, Liability for Future Policy Benefit, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Tax	84	1,480	387
Other Comprehensive Income (Loss), Tax	16	(156)	(61)
Other Comprehensive Income (Loss), Net of Tax	100	1,324	326
AOCI, Liability for Future Policy Benefit, Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(26)	0	0
AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	(24)	(57)	0
Balance – end of year, net of tax	(22)	(24)	(57)
AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Parent | Cumulative Effect, Period of Adoption, Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	0	0	(84)
Balance – end of year, net of tax		0	0
AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Parent | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	(24)	(57)	(84)
Balance – end of year, net of tax		(24)	(57)
AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	2	33	27
AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	0	0	0
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	(2,966)	(2,114)	(1,637)
Balance – end of year, net of tax	(2,945)	(2,966)	(2,114)
Cumulative Translation Adjustment | Cumulative Effect, Period of Adoption, Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	0	0	7
Balance – end of year, net of tax		0	0
Cumulative Translation Adjustment | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	(2,966)	(2,114)	(1,630)
Balance – end of year, net of tax		(2,966)	(2,114)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	(907)	(505)
Total net realized gains (losses) reclassified from AOCI	(13)	(4)	0
Other Comprehensive Income (Loss), before Tax	(13)	(911)	(505)
Other Comprehensive Income (Loss), Tax	(27)	(59)	(21)
Other Comprehensive Income (Loss), Net of Tax	14	(852)	(484)
Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(7)	0	0
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	101	17	0
Total net realized gains (losses) reclassified from AOCI	(34)	(100)	0
Other Comprehensive Income (Loss), before Tax	67	(83)	0
Other Comprehensive Income (Loss), Tax	14	(17)	0
Other Comprehensive Income (Loss), Net of Tax	53	(66)	0
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	0	0	0
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Tax	90	(17)	522
Other Comprehensive Income (Loss), Tax	18	(2)	115
Other Comprehensive Income (Loss), Net of Tax	72	(15)	407
Accumulated Defined Benefit Plans Adjustment Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	0	0	0
Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	(10,185)	(1,074)	2,869
Other Comprehensive Income (Loss), Net of Tax	3,376	(9,111)	(2,141)
Balance – end of year, net of tax	(6,809)	(10,185)	(1,074)
Accumulated Other Comprehensive Income | Cumulative Effect, Period of Adoption, Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	0	0	(1,802)
Balance – end of year, net of tax		0	0
Accumulated Other Comprehensive Income | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	$ (10,185)	(1,074)	1,067
Balance – end of year, net of tax		$ (10,185)	$ (1,074)