Net Income per Share - Reconciliation of Basic to Diluted Net Income per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net income	$ 10,326	$ 8,810
Shares used in net income per common share - basic (in shares)	28,763	25,740
Incremental shares of unvested restricted common stock (in shares)	134	19
Shares used in net income per common share - diluted (in shares)	28,897	25,759
Earnings per share:
Basic net income	$ 0.36	$ 0.34
Diluted net income	$ 0.36	$ 0.34