Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share
Net income (loss) for basic and diluted earnings (loss) per share	$ 4,643	$ (5,217)	$ 9,945	$ (7,723)
Shares of common stock and common stock equivalents:
Average common shares used in basic computation	33,125,000	33,189,000	33,037,000	33,147,000
Effect of dilutive securities (in shares)	1,097,000		1,143,000
Average common shares used in diluted computation	34,222,000	33,189,000	34,180,000	33,147,000
(Loss) income per share:
Basic (in dollars per share)	$ 0.14	$ (0.16)	$ 0.30	$ (0.23)
Diluted (in dollars per share)	$ 0.14	$ (0.16)	$ 0.29	$ (0.23)
Anti-dilutive equity awards not included in the detailed earnings per share computation
Equity awards not included in the diluted earnings per share computation	100,000	0	100,000	0