Earnings Per Common Share (Reconciliation of Earnings (loss) Per Common Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic
Net income (loss)	$ (47,573)	$ 12,453	$ (319)	$ (2,579)	$ (2,515)	$ (6,230)	$ (25,895)	$ (1,292)	$ (38,018)	$ (35,932)	$ 30,032
Weighted-average shares, outstanding									63,161	62,213	61,780
Income (loss) per common share - Basic	$ (0.75)	$ 0.20	$ (0.01)	$ (0.04)	$ (0.04)	$ (0.10)	$ (0.42)	$ (0.02)	$ (0.60)	$ (0.58)	$ 0.49
Diluted
Net income (loss)	$ (47,573)	$ 12,453	$ (319)	$ (2,579)	$ (2,515)	$ (6,230)	$ (25,895)	$ (1,292)	$ (38,018)	$ (35,932)	$ 30,032
Weighted average shares:
Weighted-average shares, outstanding									63,161	62,213	61,780
Diluted effect of outstanding stock options, restricted stock, and restricted stock unit awards									0	0	982
Weighted-average shares, Diluted									63,161	62,213	62,762
Income (loss) per common share - Diluted (USD per share)	$ (0.75)	$ 0.19	$ (0.01)	$ (0.04)	$ (0.04)	$ (0.10)	$ (0.42)	$ (0.02)	$ (0.60)	$ (0.58)	$ 0.48