Fair Value Measurements - Fair Value of Hedges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Gain (loss) recorded in other comprehensive income	$ (5)	$ (4)	$ (10)	$ (5)
Interest rate swap
Derivatives, Fair Value [Line Items]
Gain (loss) recorded in other comprehensive income	(11)	$ 4	(16)	$ 6
Interest rate swap | Other liabilities
Derivatives, Fair Value [Line Items]
Derivative fair value	17		17
Gain (loss) recorded in other comprehensive income	11		17
Interest rate swap | Other assets
Derivatives, Fair Value [Line Items]
Derivative fair value					$ 0
Cross-currency interest rate swaps | Other assets
Derivatives, Fair Value [Line Items]
Derivative fair value	29		29		$ 18
Gain (loss) recorded in other comprehensive income	$ 5		$ (11)