Shareholders' equity AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax			$ 59,507
Other comprehensive income (loss), before income tax	$ 3,205	$ (1,772)	1,601	$ (1,305)
Other Comprehensive Income (Loss), Tax	150	0	112	104
Other Comprehensive Income (Loss), Net of Tax	3,055	(1,772)	1,489	(1,409)
Balance – end of period, net of tax	65,757	52,373	65,757	52,373
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(5,301)	(6,809)	(4,177)	(7,279)
Balance – end of period, net of tax	(2,042)	(8,953)	(2,042)	(8,953)
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	3,419	(2,240)	2,139	(1,935)
Net Realized Gains (Losses) Reclassified from AOCI	(40)	(70)	(154)	(357)
Other comprehensive income (loss), before income tax	3,459	(2,170)	2,293	(1,578)
Other Comprehensive Income (Loss), Tax	198	(29)	149	93
Other Comprehensive Income (Loss), Net of Tax	3,261	(2,141)	2,144	(1,671)
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	2	3	9	3
AOCI, Liability for Future Policy Benefit, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	66	(247)	51	(75)
Balance – end of period, net of tax	(527)	404	(527)	404
AOCI, Liability for Future Policy Benefit, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before income tax	(672)	683	(672)	497
Other Comprehensive Income (Loss), Tax	(36)	35	(14)	21
Other Comprehensive Income (Loss), Net of Tax	(636)	648	(658)	476
AOCI, Liability for Future Policy Benefit, Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(43)	(3)	(80)	(3)
AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(13)	(16)	(22)	(24)
Balance – end of period, net of tax	(20)	(21)	(20)	(21)
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 income tax	(8)	(5)	2	3
Other Comprehensive Income (Loss), Tax	(1)	0	0	0
Other Comprehensive Income (Loss), Net of Tax	(7)	(5)	2	3
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	0
Cumulative Foreign Currency Translation Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(3,342)	(2,920)	(2,945)	(2,966)
Balance – end of period, net of tax	(2,952)	(3,148)	(2,952)	(3,148)
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	450	(314)	6	(269)
Net Realized Gains (Losses) Reclassified from AOCI	5	3	11	10
Other comprehensive income (loss), before income tax	445	(317)	(5)	(279)
Other Comprehensive Income (Loss), Tax	(7)	(13)	(19)	(21)
Other Comprehensive Income (Loss), Net of Tax	452	(304)	14	(258)
Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	62	(76)	21	(76)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(11)	(53)	(13)	(66)
Balance – end of period, net of tax	(25)	(22)	(25)	(22)
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	42	(17)	(12)	23
Net Realized Gains (Losses) Reclassified from AOCI	60	(55)	3	(32)
Other comprehensive income (loss), before income tax	(18)	38	(15)	55
Other Comprehensive Income (Loss), Tax	(4)	7	(3)	11
Other Comprehensive Income (Loss), Net of Tax	(14)	31	(12)	44
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	0
Postretirement Benefit Liability Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	297	223	297	225
Balance – end of period, net of tax	296	222	296	222
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 income tax	(1)	(1)	(2)	(3)
Other Comprehensive Income (Loss), Tax	0	0	(1)	0
Other Comprehensive Income (Loss), Net of Tax	(1)	(1)	(1)	(3)
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	0
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(8,304)	(9,822)	(6,809)	(10,185)
Other Comprehensive Income (Loss), Net of Tax	3,034	(1,696)	1,539	(1,333)
Balance – end of period, net of tax	$ (5,270)	$ (11,518)	$ (5,270)	$ (11,518)