Fair Value Measurements - Gains and Losses on Derivative Financial Instruments (Details) - Fair Value, Measurements, Recurring - Cost of Sales - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Foreign exchange forward contracts
Derivatives, Fair Value [Line Items]
Recorded into gain (loss)	$ 0	$ 0	$ 0	$ 0
Recorded gains (loss) into AOCI net of tax	0	(3)	0	(6)
Less: Reclassified from AOCI gain (loss)	0	2	(1)	5
Gains and losses on derivative financial instruments	0	(4)	(1)	(10)
Foreign exchange swaps
Derivatives, Fair Value [Line Items]
Recorded into gain (loss)	(1)	(1)	0	1
Recorded gains (loss) into AOCI net of tax	0	0	0	0
Less: Reclassified from AOCI gain (loss)	0	0	0	0
Gains and losses on derivative financial instruments	$ (1)	$ (1)	$ 0	$ 1