Earnings (Loss) and Dividends per Share - Number of Shares Outstanding for Calculation of Earnings (Loss) Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Basic net income(loss) and earnings (loss) per share, Numerator (Income)	$ (4,825)	$ 3,703	$ (2,523)	$ 11,217
Common stock equivalents arising from stock options and employee stock purchase plan, Numerator (Income)	0	0	0	0
Diluted earnings (loss) and earnings (loss) per share, Numerator (Income)	$ (4,825)	$ 3,703	$ (2,523)	$ 11,217
Basic net income (loss) and earnings (loss) per share, Denominator (Shares)	28,617,589	25,691,884	27,066,072	25,647,561
Common stock equivalents arising from stock options and employee stock purchase plan, Denominator (Shares)		437,000		458,000
Diluted earnings (loss) and earnings (loss) per share, Denominator (Shares)	28,617,589	26,129,427	27,066,072	26,105,415
Basic net income (loss) and earning (loss) per share, Per Share Amount	$ (0.17)	$ 0.14	$ (0.09)	$ 0.44
Common stock equivalents arising from stock options and employee stock purchase plan, Per Share Amount				(0.01)
Diluted earning (loss) and earning (loss) per share, Per Share Amount	$ (0.17)	$ 0.14	$ (0.09)	$ 0.43