Accumulated Other Comprehensive Income (Loss) (AOCI) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), beginning balance	$ (199)
Tax Cuts and Jobs Act Reclassification from AOCI to Retained Earnings Tax Effect	1	$ 0
Other comprehensive (loss) income before reclassifications	14
Amounts reclassified from AOCI	0
Net current period other comprehensive (loss) income	15
Accumulated other comprehensive income (loss), ending balance	(184)
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), beginning balance	(183)
Tax Cuts and Jobs Act Reclassification from AOCI to Retained Earnings Tax Effect	0
Other comprehensive (loss) income before reclassifications	19
Amounts reclassified from AOCI	0
Net current period other comprehensive (loss) income	19
Accumulated other comprehensive income (loss), ending balance	(164)
Changes in Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), beginning balance	(15)
Tax Cuts and Jobs Act Reclassification from AOCI to Retained Earnings Tax Effect	1
Other comprehensive (loss) income before reclassifications	0
Amounts reclassified from AOCI	(1)
Net current period other comprehensive (loss) income	0
Accumulated other comprehensive income (loss), ending balance	(15)
Changes in Fair Value of Effective Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), beginning balance	(1)
Tax Cuts and Jobs Act Reclassification from AOCI to Retained Earnings Tax Effect	0
Other comprehensive (loss) income before reclassifications	(5)
Amounts reclassified from AOCI	1
Net current period other comprehensive (loss) income	(4)
Accumulated other comprehensive income (loss), ending balance	$ (5)