Summary of Significant Accounting Policies - Components of Other Expense, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Regulatory Assets [Abstract]
Interest expense, net	$ 100	$ 18	$ 15
Accretion of contingent earnout consideration	2,182	1,710
Loss on foreign exchange transactions	45	285	166
Other expense, net	$ 2,327	$ 2,013	$ 181