Revenue - Performance obligation (Details) $ in Millions	6 Months Ended
Jun. 30, 2020 USD ($)
Revenue from Contract with Customer [Abstract]
Price allocated to remaining performance obligations	$ 314
Revenue recognition for remaining performance obligations	251
Revenue Recognition for Remaining Performance Obligations in next 24 months	$ 63

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130556-203045

Name:	us-gaap_RevenueRemainingPerformanceObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant