Geographical Data - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenue	$ 14,799	$ 19,218
Domestic
Segment Reporting Information [Line Items]
Revenue	10,393	14,070
Foreign
Segment Reporting Information [Line Items]
Revenue	$ 4,406	$ 5,148

Aggregate revenue during the period from services rendered in the normal course of business, after deducting allowances and discounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(d))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_SalesRevenueServicesNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration