Shareholders' equity AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax			$ 50,519
Balance – end of period, net of tax	$ 52,875	$ 51,268	52,875	$ 51,268
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	(5,659)	(1,584)	(7,279)	2,256
OCI, before Reclassifications, before Tax, Attributable to Parent	(1,301)	(4,786)	305	(9,574)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	107	442	287	578
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	(1,194)	(4,344)	592	(8,996)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	44	215	(122)	1,027
Balance – end of period, net of tax	(6,809)	(5,713)	(6,809)	(5,713)
AOCI, Liability for Future Policy Benefit, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(205)	(997)	(75)	(1,399)
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	(35)	632	(186)	1,067
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(7)	(62)	14	(95)
Balance – end of period, net of tax	(247)	(427)	(247)	(427)
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	(27)	(34)	(24)	(57)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	11	17	8	40
Balance – end of period, net of tax	(16)	(17)	(16)	(17)
Cumulative Foreign Currency Translation Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(3,136)	(2,043)	(2,966)	(2,114)
OCI, before Reclassifications, before Tax, Attributable to Parent	219	(756)	45	(689)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	(4)	0	(7)	0
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	215	(756)	38	(689)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	1	31	8	35
Balance – end of period, net of tax	(2,920)	(2,768)	(2,920)	(2,768)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(92)	0	(66)	0
OCI, before Reclassifications, before Tax, Attributable to Parent	57	0	40	0
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	(7)	0	(23)	0
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	50	0	17	0
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(11)	0	(4)	0
Balance – end of period, net of tax	(53)	0	(53)	0
Postretirement Benefit Liability Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	224	255	225	240
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	(2)	5	(2)	24
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	1	(1)	0	(5)
Balance – end of period, net of tax	223	259	223	259
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(8,895)	(4,403)	(10,185)	(1,074)
Balance – end of period, net of tax	$ (9,822)	$ (8,666)	$ (9,822)	$ (8,666)