Net Income Per Share - Schedule of Earnings Per Share, Basic and Diluted (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net income, as reported	$ 6,653	$ 5,904	$ 12,011	$ 13,261
Less: net income attributable to participating securities	(206)	(150)	(343)	(301)
Net income available to common shareholders-basic	$ 6,447	$ 5,754	$ 11,668	$ 12,960
Basic:
Weighted-average shares of common stock outstanding	40,721,081	39,873,730	40,475,785	39,758,947
Less: weighted-average shares of unvested restricted common stock outstanding	(1,343,136)	(1,047,545)	(1,225,488)	(931,279)
Weighted-average number of common shares used in computing basic net income per common share	39,377,945	38,826,185	39,250,297	38,827,668
Net income per share applicable to common shareholders-basic	$ 0.16	$ 0.15	$ 0.30	$ 0.33
Net income available to common shareholders-basic	$ 6,447	$ 5,754	$ 11,668	$ 12,960
Add-back: undistributed earnings allocated to unvested shareholders	72	51	95	124
Less: undistributed earnings reallocated to unvested shareholders	(72)	(50)	(94)	(122)
Net income available to common shareholders-diluted	$ 6,447	$ 5,755	$ 11,669	$ 12,962
Weighted-average shares of common stock outstanding	40,721,081	39,873,730	40,475,785	39,758,947
Less: weighted-average shares of unvested restricted common stock outstanding	(1,343,136)	(1,047,545)	(1,225,488)	(931,279)
Weighted-average number of common shares used in computing diluted net income per common share	39,748,905	39,395,395	39,635,262	39,458,758
Net income per share applicable to common shareholders-diluted	$ 0.16	$ 0.15	$ 0.29	$ 0.33
Weighted Average [Member]
Basic:
Weighted-average number of common shares issuable upon exercise of outstanding stock options, based on the treasury stock method	370,960	569,210	384,965	631,090