Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Loss
Balance at the beginning of the period	$ (1,013)
Amount reclassified from accumulated OCI	4	$ 4
Tax provision		1
Balance at end of the period	(972)
Cumulative Translation Adjustment
Accumulated Other Comprehensive Loss
Balance at the beginning of the period	(951)	(1,008)
Other comprehensive income (loss) before reclassification adjustments	21	40
Net other comprehensive income (loss)	21	40
Balance at end of the period	(930)	(968)
Deferred (Loss) Gain on Hedging Activities
Accumulated Other Comprehensive Loss
Balance at the beginning of the period	(13)	(7)
Other comprehensive income (loss) before reclassification adjustments	22	8
Amount reclassified from accumulated OCI	4	4
Tax provision	(6)	(4)
Net other comprehensive income (loss)	20	8
Balance at end of the period	7	1
Pension and Postretirement Adjustment
Accumulated Other Comprehensive Loss
Balance at the beginning of the period	(51)	(56)
Other comprehensive income (loss) before reclassification adjustments	(1)
Net other comprehensive income (loss)	(1)
Balance at end of the period	(52)	(56)
Unrealized (Loss) Gain on Investment
Accumulated Other Comprehensive Loss
Balance at the beginning of the period	2
Other comprehensive income (loss) before reclassification adjustments	1
Net other comprehensive income (loss)	1
Balance at end of the period	3
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Loss
Balance at the beginning of the period	(1,013)	(1,071)
Other comprehensive income (loss) before reclassification adjustments	43	48
Amount reclassified from accumulated OCI	4	4
Tax provision	(6)	(4)
Net other comprehensive income (loss)	41	48
Balance at end of the period	$ (972)	$ (1,023)