Balance Sheet Components - Other Current Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Balance Sheet Components [Abstract]
Customer accounts and funds receivable	$ 662	$ 590
Other	523	544
Other current assets	$ 1,185	$ 1,134

Amount of current assets classified as other.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.8)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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