Derivative Instruments - Location and Fair Values of Cash Flow Hedges (Details) - Cash Flow Hedging - Foreign exchange forward contracts - Designated as Hedging Instrument - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Prepaid and other current assets
Derivatives, Fair Value [Line Items]
Derivative, fair value	$ 1	$ 3
Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative, fair value	$ (7)	$ 0

Fair value of the assets less the liabilities of a derivative or group of derivatives.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant