Financial Instruments - AOCI (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value
Accumulated other comprehensive income (loss), cumulative changes in net gain (loss) from hedges, before tax	$ (93)	$ 4
Gain (loss) expected to be reclassified to income in one year or less	(1)
Foreign currency
Derivatives, Fair Value
Accumulated other comprehensive income (loss), cumulative changes in net gain (loss) from hedges, before tax	(1)	0
Gain (loss) expected to be reclassified to income in one year or less	(1)
Foreign currency | Net investment hedge
Derivatives, Fair Value
Accumulated other comprehensive income (loss), cumulative changes in net gain (loss) from hedges, before tax	6	5
Gain (loss) expected to be reclassified to income in one year or less	0
Cross-currency swaps | Net investment hedge
Derivatives, Fair Value
Accumulated other comprehensive income (loss), cumulative changes in net gain (loss) from hedges, before tax	(55)	16
Gain (loss) expected to be reclassified to income in one year or less	0
Foreign currency-denominated debt | Net investment hedge
Derivatives, Fair Value
Accumulated other comprehensive income (loss), cumulative changes in net gain (loss) from hedges, before tax	(43)	$ (17)
Gain (loss) expected to be reclassified to income in one year or less	$ 0