Segment Information - Geographical Segment Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total	$ 5,576	$ 5,386	$ 16,613	$ 17,173
Domestic [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total	1,210	1,733	3,494	5,178
International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total	$ 4,366	$ 3,653	$ 13,119	$ 11,995