Segment, Customer Concentration and Geographical Information - Company Revenue in Different Geographic Locations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue from External Customer [Line Items]
Total revenues	$ 5,804	$ 6,478	$ 17,242	$ 21,151
Americas [Member] | Reportable Geographical Components [Member]
Revenue from External Customer [Line Items]
Total revenues	5,713	6,218	16,949	20,662
EMEA [Member] | Reportable Geographical Components [Member]
Revenue from External Customer [Line Items]
Total revenues	43	203	124	367
Asia Pacific [Member] | Reportable Geographical Components [Member]
Revenue from External Customer [Line Items]
Total revenues	$ 48	$ 57	$ 169	$ 122