Fair Value Measurements - Schedule of Derivatives Recorded in Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Carrying Amount of the Hedged Liability	$ 272	$ 367
Current Portion of Long-term Debt
Derivative Instruments, Gain (Loss) [Line Items]
Carrying Amount of the Hedged Liability	601	597
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Liability	1	2
Long-term Debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Carrying Amount of the Hedged Liability	495	496
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Liability	$ (4)	$ 3