Revenue - Performance Obligations - General Information (Details) $ in Thousands	Jun. 30, 2018 USD ($)
Customers, Contracted Revenue, Deferred Revenue
Remaining performance obligations
Remaining performance obligation	$ 169,271
Customers, Contracted Revenue, Backlog
Remaining performance obligations
Remaining performance obligation	$ 42,963

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=109196051&loc=SL49130556-203045

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