Revenue, Contract Liabilities (Details) $ in Thousands	3 Months Ended
Mar. 31, 2018 USD ($)
Contract with Customer, Liability [Abstract]
Short-term contract liabilities	$ 89
Long-term contract liabilities	175
Change in Contract with Customer, Liability [Abstract]
Contract liabilities recognized as revenue	$ 7

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130549-203045

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130532-203044

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