Fair Value Measurements - Fair Value of Hedges (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Gain (loss) recorded in other comprehensive income	$ (5)	$ (4)	$ (15)	$ (9)
Interest rate swap
Derivatives, Fair Value [Line Items]
Gain (loss) recorded in other comprehensive income	3	$ 3	(13)	$ 9
Interest rate swap | Other liabilities
Derivatives, Fair Value [Line Items]
Derivative fair value	19		19		$ 0
Gain (loss) recorded in other comprehensive income	2		19
Interest rate swap | Other assets
Derivatives, Fair Value [Line Items]
Derivative fair value	55		55		$ 18
Cross-currency interest rate swaps | Other assets
Derivatives, Fair Value [Line Items]
Gain (loss) recorded in other comprehensive income	$ (26)		$ (37)