Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income (Loss) per Common Share - Basic
Net (loss) income for year	$ (1,126)	$ 21,637
Weighted-average number of common shares outstanding	44,215	44,197
Basic (loss) income per share (in dollars per share)	$ (0.03)	$ 0.49
Income (Loss) per Common Share - Diluted
Net (loss) income for year	$ (1,126)	$ 21,637
Weighted-average number of common shares outstanding	44,215	44,197
Weighted-average incremental shares related to assumed exercise of stock options, vesting of nonvested shares, and ESPP	0	23
Weighted-average common shares outstanding and common share equivalents	44,215	44,220
Diluted (loss) income per share (in dollars per share)	$ (0.03)	$ 0.49