Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net Income	$ 17,478	$ 12,234	$ 33,248	$ 25,123
Denominator:
Weighted average basic shares	29,545	28,171	29,608	28,194
Dilutive potential common shares	606	433	582	443
Weighted average fully diluted shares	30,151	28,604	30,190	28,637
Earnings per share:
Basic	$ 0.59	$ 0.43	$ 1.12	$ 0.89
Diluted	$ 0.58	$ 0.43	$ 1.10	$ 0.88
Outstanding common stock equivalents having no dilutive effect	5	184	20	184