Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Balances as of January 1	$ (2,428)
Net unrealized pension and other postretirement benefit, net of tax	11	$ 62	$ 19
Balances as of December 31	(2,597)	(2,428)
Tax impact for the changes in each component of accumulated other comprehensive (loss) income
Investment securities	(2)	(4)	(27)
Foreign currency translation adjustments	(44)	(172)	(15)
Net investment hedges	107	(215)	139
Pension and other postretirement benefit losses	9	7	37
Total tax impact	70	(384)	134
Accumulated Other Comprehensive (Loss) Income [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Balances as of January 1	(2,428)	(2,784)	(2,534)
Net unrealized gains (losses)	(10)	(7)	(45)
Reclassification for realized (gains) losses into earnings	0	(7)	(2)
Net translation of investments in foreign operations	(500)	678	(503)
Net gains (losses) related to hedges of investment in foreign operations	328	(370)	281
Net unrealized pension and other postretirement benefit, net of tax	11	62	19
Net change in accumulated other comprehensive (loss) income	(169)	356	(250)
Balances as of December 31	(2,597)	(2,428)	(2,784)
Other - Net Unrealized Gains (Losses) on Equity Securities	2
Net Unrealized Investment Gains (Losses) on Investment Securities [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Balances as of January 1	0	7	58
Net unrealized gains (losses)	(10)	(7)	(45)
Reclassification for realized (gains) losses into earnings	0	0	(6)
Net translation of investments in foreign operations	0	0	0
Net gains (losses) related to hedges of investment in foreign operations	0	0	0
Net unrealized pension and other postretirement benefit, net of tax	0	0	0
Net change in accumulated other comprehensive (loss) income	(8)	(7)	(51)
Balances as of December 31	(8)	0	7
Other - Net Unrealized Gains (Losses) on Equity Securities	2
Foreign Currency Translation Adjustments [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Balances as of January 1	(1,961)	(2,262)	(2,044)
Net unrealized gains (losses)	0	0	0
Reclassification for realized (gains) losses into earnings	0	(7)	4
Net translation of investments in foreign operations	(500)	678	(503)
Net gains (losses) related to hedges of investment in foreign operations	328	(370)	281
Net unrealized pension and other postretirement benefit, net of tax	0	0	0
Net change in accumulated other comprehensive (loss) income	(172)	301	(218)
Balances as of December 31	(2,133)	(1,961)	(2,262)
Other - Net Unrealized Gains (Losses) on Equity Securities	0
Net Unrealized Pension and Other Postretirement Benefit (Losses) Gains [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Balances as of January 1	(467)	(529)	(548)
Net unrealized gains (losses)	0	0	0
Reclassification for realized (gains) losses into earnings	0	0	0
Net translation of investments in foreign operations	0	0	0
Net gains (losses) related to hedges of investment in foreign operations	0	0	0
Net unrealized pension and other postretirement benefit, net of tax	11	62	19
Net change in accumulated other comprehensive (loss) income	11	62	19
Balances as of December 31	(456)	$ (467)	$ (529)
Other - Net Unrealized Gains (Losses) on Equity Securities	$ 0