Stockholders' Equity - Basic and Diluted Net Income Per Common Shares (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator:
Net income	$ 1,498	$ 3,451	$ 2,352	$ 6,895
Denominator:
Weighted average shares used to compute net income per common share - basic (shares)	20,353,801	20,568,058	20,441,781	20,637,070
Weighted average shares used to compute net income per common share - diluted (shares)	20,366,102	20,568,058	20,508,473	20,637,070
Basic net income per common share (usd per share)	$ 0.07	$ 0.17	$ 0.12	$ 0.33
Diluted net income per common share (usd per share)	$ 0.07	$ 0.17	$ 0.11	$ 0.33