Stock-based Compensation - Warrants Granted to Non-Employees - General Information 10-K (Details) - Stock warrants - Non-Employee - $ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Warrant information
Class of Warrant or Right, Vested	305,775	305,775
Class of Warrant or Right, Outstanding	305,775	305,775
Warrants, exercise price (in dollars per share)	$ 2.57	$ 2.57

Exercise price per share or per unit of warrants or rights outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant