Changes in Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning balance	$ (2,597)
Net unrealized Pension and other postretirement benefits, net of tax	(27)	$ 28
Balance as of end of period	(2,599)
Tax impact for the changes in each component of accumulated other comprehensive (loss) income
Investment securities	4	(3)
Foreign currency translation adjustments	14	2
Net investment hedges	(50)	(54)
Pension and other postretirement benefits	(11)	3
Total tax impact	(43)	(52)
Accumulated Other Comprehensive Loss [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning balance	(2,597)	(2,428)
Net unrealized gains	17	(13)
Net translation of investments in foreign operations	170	192
Net gains (losses) related to hedges of investment in foreign operations	(162)	(162)
Net unrealized Pension and other postretirement benefits, net of tax	(27)	28
Other - Net Unrealized Gains (Losses) on Equity Securities		2
Net change in accumulated other comprehensive (loss) income	(2)	47
Balance as of end of period	(2,599)	(2,381)
Net Unrealized Gains (Losses) on Investment Securities [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning balance	(8)	0
Net unrealized gains	17	(13)
Net translation of investments in foreign operations	0	0
Net gains (losses) related to hedges of investment in foreign operations	0	0
Net unrealized Pension and other postretirement benefits, net of tax	0	0
Other - Net Unrealized Gains (Losses) on Equity Securities		2
Net change in accumulated other comprehensive (loss) income	17	(11)
Balance as of end of period	9	(11)
Foreign Currency Translation Adjustments [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning balance	(2,133)	(1,961)
Net unrealized gains	0	0
Net translation of investments in foreign operations	170	192
Net gains (losses) related to hedges of investment in foreign operations	(162)	(162)
Net unrealized Pension and other postretirement benefits, net of tax	0	0
Other - Net Unrealized Gains (Losses) on Equity Securities		0
Net change in accumulated other comprehensive (loss) income	8	30
Balance as of end of period	(2,125)	(1,931)
Net Unrealized Pension and Other Postretirement Gains (Losses) [Member]
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning balance	(456)	(467)
Net unrealized gains	0	0
Net translation of investments in foreign operations	0	0
Net gains (losses) related to hedges of investment in foreign operations	0	0
Net unrealized Pension and other postretirement benefits, net of tax	(27)	28
Other - Net Unrealized Gains (Losses) on Equity Securities		0
Net change in accumulated other comprehensive (loss) income	(27)	28
Balance as of end of period	$ (483)	$ (439)