Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance	$ 22,290	$ 18,261	$ 20,523
Net unrealized gains (losses)	41	(10)	(7)
Decrease due to amounts reclassified into earnings			(7)
Net translation of investments in foreign operations	84	(500)	678
Net gains (losses) related to hedges of investment in foreign operations		328	(370)
Net gains (losses) related to hedges of investments in foreign operations	(140)
Pension and other postretirement benefits	(125)	11	62
Other		2
Net change in accumulated other comprehensive (loss) income	(140)	(169)	356
Ending Balance	23,071	22,290	18,261
Tax impact for the changes in each component of accumulated other comprehensive (loss) income
Investment securities	12	(2)	(4)
Foreign currency translation adjustments	24	(44)	(172)
Net investment hedges	(43)	107	(215)
Pension and other postretirement benefit losses	(38)	9	7
Total tax impact	(45)	70	(384)
Accumulated Other Comprehensive Loss [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance	(2,597)	(2,428)	(2,784)
Ending Balance	(2,737)	(2,597)	(2,428)
Net Unrealized Investment Gains (Losses) on Investment Securities [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance	(8)	0	7
Net unrealized gains (losses)	41	(10)	(7)
Decrease due to amounts reclassified into earnings			0
Net translation of investments in foreign operations	0	0	0
Net gains (losses) related to hedges of investment in foreign operations		0	0
Net gains (losses) related to hedges of investments in foreign operations	0
Pension and other postretirement benefits	0	0	0
Other		(2)
Net change in accumulated other comprehensive (loss) income	41	(8)	(7)
Ending Balance	33	(8)	0
Foreign Currency Translation Adjustments [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance	(2,133)	(1,961)	(2,262)
Net unrealized gains (losses)	0	0	0
Decrease due to amounts reclassified into earnings			(7)
Net translation of investments in foreign operations	84	(500)	678
Net gains (losses) related to hedges of investment in foreign operations		328	(370)
Net gains (losses) related to hedges of investments in foreign operations	(140)
Pension and other postretirement benefits	0	0	0
Other		0
Net change in accumulated other comprehensive (loss) income	(56)	(172)	301
Ending Balance	(2,189)	(2,133)	(1,961)
Net Unrealized Pension and Other Postretirement Benefit (Losses) Gains [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance	(456)	(467)	(529)
Net unrealized gains (losses)	0	0	0
Decrease due to amounts reclassified into earnings			0
Net translation of investments in foreign operations	0	0	0
Net gains (losses) related to hedges of investment in foreign operations		0	0
Net gains (losses) related to hedges of investments in foreign operations	0
Pension and other postretirement benefits	(125)	11	62
Other		0
Net change in accumulated other comprehensive (loss) income	(125)	11	62
Ending Balance	$ (581)	$ (456)	$ (467)