Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Numerator for calculation of diluted earnings per share
Net income	$ (52,897)	$ (2,148)	$ (57,577)	$ (17,774)
Denominator for diluted income per share
Weighted-average shares outstanding	61,028	60,818	60,982	60,779
Denominator for diluted earnings per share (in shares)	61,028	60,818	60,982	60,779
Diluted earnings per share (in dollars per share)	$ (0.87)	$ (0.04)	$ (0.94)	$ (0.29)
Stock Compensation Plan [Member]
Anti-dilutive securities excluded from diluted earnings (loss) per share calculation
Anti-dilutive stock equivalents	2,199	1,394	2,005	1,390