Derivative Instruments - Fair Value Amounts of Cash Flow Hedges (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Foreign exchange forward contracts \| Prepaid and other current assets \| Designated as hedging instrument \| Cash flow hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, fair value, net	$ 3	$ 3

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

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