Geographic Information - Schedule of Geographic Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Total revenue	$ 27,361	$ 30,826	$ 86,796	$ 96,748
UNITED STATES
Segment Reporting Information [Line Items]
Total revenue	24,488	26,654	76,842	82,342
CANADA
Segment Reporting Information [Line Items]
Total revenue	2,218	2,108	7,365	8,847
Non-US [Member]
Segment Reporting Information [Line Items]
Total revenue	$ 655	$ 2,064	$ 2,589	$ 5,559