Property and Equipment - Depreciation and Amortization on Property and Equipment Using the Straight-Line Method (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Abstract]
Office furniture and fixtures	$ 1,168	$ 1,068
Software	2,146	1,748
Equipment	4,071	3,416
Leasehold improvements	1,617	1,276
Gross property and equipment	9,002	7,508
Less accumulated depreciation and amortization	(5,432)	(4,498)
Property and equipment, net	$ 3,570	$ 3,010