Shareholders' equity AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	$ 59,507	$ 50,519
Other Comprehensive Income (Loss), before Tax	(1,865)	3,678	$ (10,076)
Other Comprehensive Income (Loss), Tax	117	317	(965)
Other Comprehensive Income (Loss), Net of Tax	(1,982)	3,361	(9,111)
Balance – end of year, net of tax	64,021	59,507	50,519
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	(4,177)	(7,279)	2,256
Balance – end of year, net of tax	(4,552)	(4,177)	(7,279)
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	(553)	2,948	(11,627)
Total net realized gains (losses) reclassified from AOCI	302	500	1,049
Other Comprehensive Income (Loss), before Tax	(251)	3,448	(10,578)
Other Comprehensive Income (Loss), Tax	110	328	(1,043)
Other Comprehensive Income (Loss), Net of Tax	(361)	3,120	(9,535)
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	14	18	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	(13)	(66)	0
Balance – end of year, net of tax	50	(13)	(66)
Accumulated Defined Benefit Plans Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	297	225	240
Balance – end of year, net of tax	438	297	225
AOCI, Liability for Future Policy Benefit, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of year, net of tax	51	(75)	(1,399)
Balance – end of year, net of tax	(539)	51	(75)
AOCI, Liability for Future Policy Benefit, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Tax	(701)	84	1,480
Other Comprehensive Income (Loss), Tax	8	16	(156)
Other Comprehensive Income (Loss), Net of Tax	(693)	100	1,324
AOCI, Liability for Future Policy Benefit, Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(103)	(26)	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	(22)	(24)	(57)
Balance – end of year, net of tax	(16)	(22)	(24)
AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Tax	7	2	33
Other Comprehensive Income (Loss), Tax	(1)	0	0
Other Comprehensive Income (Loss), Net of Tax	6	2	33
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	(2,945)	(2,966)	(2,114)
Balance – end of year, net of tax	(4,025)	(2,945)	(2,966)
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	(1,158)	0	(907)
Total net realized gains (losses) reclassified from AOCI	(19)	(13)	(4)
Other Comprehensive Income (Loss), before Tax	(1,177)	(13)	(911)
Other Comprehensive Income (Loss), Tax	(39)	(27)	(59)
Other Comprehensive Income (Loss), Net of Tax	(1,138)	14	(852)
Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(58)	(7)	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	(38)	101	17
Total net realized gains (losses) reclassified from AOCI	118	(34)	(100)
Other Comprehensive Income (Loss), before Tax	80	67	(83)
Other Comprehensive Income (Loss), Tax	17	14	(17)
Other Comprehensive Income (Loss), Net of Tax	63	53	(66)
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	177	90	(17)
Other Comprehensive Income (Loss), Tax	36	18	(2)
Other Comprehensive Income (Loss), Net of Tax	141	72	(15)
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	(6,809)	(10,185)	(1,074)
Other Comprehensive Income (Loss), Net of Tax	(1,835)	3,376	(9,111)
Balance – end of year, net of tax	$ (8,644)	$ (6,809)	$ (10,185)