Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss	$ (3,042)	$ (2,224)	$ (2,350)	$ (2,300)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(758)	31
Other Comprehensive Income (Loss), Before Reclassifications, Tax	61	43
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5	2
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(692)	76
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	7	6
Tax cost related to unrealized currency translation adjustments other than translation of foreign denominated balance sheets	19	17
Pension and other postretirement benefit adjustments, tax cost	2	1
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss	(2,323)	(1,652)	(1,627)	(1,734)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(758)	31
Other Comprehensive Income (Loss), Before Reclassifications, Tax	62	51
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(696)	82
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss	(723)	(574)	(724)	(568)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Before Reclassifications, Tax	(4)	(8)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5	2
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	1	(6)
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss	4	2	$ 1	$ 2
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Before Reclassifications, Tax	3	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ 3	$ 0