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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Basic net (loss) income and (loss) earnings per share, Numerator (Loss) Income	$ (12,915)	$ 3,036	$ (8,053)	$ 8,560
Diluted (loss) earnings and (loss) earnings per share, Numerator (Loss) Income	$ (12,915)	$ 3,036	$ (8,053)	$ 8,560
Basic net (loss) income and (loss) earnings per share, Denomiator (Shares)	34,779,125	34,518,622	34,681,262	34,403,720
Common stock equivalents arising from stock options, restricted stock awards, and employee stock purchase plan, Denominator (Shares)		103,000		261,000
Diluted (loss) earnings and (loss) earnings per share, Denominator (Shares)	34,779,125	34,621,883	34,681,262	34,665,053
Basic net (loss) income and (loss) earnings per share, Per Share Amount	$ (0.37)	$ 0.09	$ (0.23)	$ 0.25
Diluted (loss) earnings and (loss) earnings per share, Per Share Amount	$ (0.37)	$ 0.09	$ (0.23)	$ 0.25