Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share
Net loss for basic and diluted loss per share	$ (46,967)	$ (23,911)	$ (37,022)	$ (31,634)
Shares of common stock and common stock equivalents:
Average common shares used in basic computation	33,105	32,725	33,060	33,006
Average common shares used in diluted computation	33,105	32,725	33,060	33,006
Loss per share:
Basic (in dollars per share)	$ (1.42)	$ (0.73)	$ (1.12)	$ (0.96)
Diluted (in dollars per share)	$ (1.42)	$ (0.73)	$ (1.12)	$ (0.96)
Anti-dilutive equity awards not included in the detailed earnings per share computation
Equity awards not included in the diluted earnings per share computation	0	0	0	0