Earnings Per Share - Summary of Calculation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator
Net Income	$ 7,067	$ 11,326	$ 12,928	$ 35,328
Denominator
Weighted average number of shares - basic	49,862	54,521	51,682	55,552
Effect of dilutive securities
Stock options	29	266	94	402
Restricted stock and restricted stock units	36	37	16	22
Weighted average number of shares - diluted	49,927	54,824	51,792	55,976
Net income per share - basic	$ 0.14	$ 0.21	$ 0.25	$ 0.64
Net income per share - diluted	$ 0.14	$ 0.21	$ 0.25	$ 0.63