Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ (2,597)
Pension and other postretirement benefits	$ 1	$ 9	(23)	$ 38
Balance as of end of period	(2,661)		(2,661)
Tax impact for the changes in each component of accumulated other comprehensive (loss) income
Investment securities	1	(4)	14	(9)
Foreign currency translation adjustments	(4)	8	11	(60)
Net investment hedges	45	(7)	23	46
Pension and other postretirement benefits	2	3	(5)	12
Total tax impact	44	0	43	(11)
Net Unrealized Gains (Losses) on Investment Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	35	(18)	(8)	0
Net unrealized gains	3	(11)	46	(31)
Net translation gains (losses) on investments in foreign operations	0	0	0	0
Net gains (losses) related to hedges of investments in foreign operations	0	0	0	0
Pension and other postretirement benefits	0	0	0	0
Other				2
Net change in accumulated other comprehensive income (loss)	3	(11)	46	(29)
Balance as of end of period	38	(29)	38	(29)
Foreign Currency Translation Adjustments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,161)	(2,027)	(2,133)	(1,961)
Net unrealized gains	0	0	0	0
Net translation gains (losses) on investments in foreign operations	(197)	3	(150)	(221)
Net gains (losses) related to hedges of investments in foreign operations	138	(22)	63	136
Pension and other postretirement benefits	0	0	0	0
Other				0
Net change in accumulated other comprehensive income (loss)	(59)	(19)	(87)	(85)
Balance as of end of period	(2,220)	(2,046)	(2,220)	(2,046)
Net Unrealized Pension and Other Postretirement Gains (Losses) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(480)	(438)	(456)	(467)
Net unrealized gains	0	0	0	0
Net translation gains (losses) on investments in foreign operations	0	0	0	0
Net gains (losses) related to hedges of investments in foreign operations	0	0	0	0
Pension and other postretirement benefits	1	9	(23)	38
Other				0
Net change in accumulated other comprehensive income (loss)	1	9	(23)	38
Balance as of end of period	(479)	(429)	(479)	(429)
Accumulated Other Comprehensive (Loss) Income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,606)	(2,483)	(2,597)	(2,428)
Net unrealized gains	3	(11)	46	(31)
Net translation gains (losses) on investments in foreign operations	(197)	3	(150)	(221)
Net gains (losses) related to hedges of investments in foreign operations	138	(22)	63	136
Pension and other postretirement benefits	1	9	(23)	38
Other				2
Net change in accumulated other comprehensive income (loss)	(55)	(21)	(64)	(76)
Balance as of end of period	$ (2,661)	$ (2,504)	$ (2,661)	$ (2,504)