Net Income Per Share (Calculation of Net Income per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income	$ 10,333	$ 6,982	$ 21,558	$ 17,910
Basic:
Basic weighted average EPS shares	24,626	25,062	24,776	25,031
Basic net income per share	$ 0.42	$ 0.28	$ 0.87	$ 0.72
Diluted:
Basic weighted average EPS shares	24,626	25,062	24,776	25,031
Dilutive common stock equivalents	64	65	92	95
Dilutive EPS shares	24,690	25,127	24,868	25,126
Diluted net income per share	$ 0.42	$ 0.28	$ 0.87	$ 0.71
Anti-dilutive shares	8	65	8	56