Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Shares that would be added to EPS calculation if the Company had generated net income	Jun. 30, 2014 Stock options and other stock awards	Jun. 30, 2013 Stock options and other stock awards	Jun. 30, 2014 Stock options and other stock awards	Jun. 30, 2013 Stock options and other stock awards	Jun. 30, 2014 4.25% Convertible Senior Notes	Dec. 31, 2013 4.25% Convertible Senior Notes	Jun. 30, 2013 4.25% Convertible Senior Notes
Earnings Per Share [Abstract]
Net income (loss)	$ 17,836	$ 31,100	$ (6,767)	$ 33,477
Weighted average common shares outstanding (used to calculate basic EPS) (in shares)	46,915,000	46,481,000	46,883,000	46,426,000
Dilutive effect of stock options and other stock awards (in shares)	1,212,000	835,000	0	769,000
Weighted average common shares outstanding (used to calculate diluted EPS) (in shares)	48,127,000	47,316,000	46,883,000	47,195,000
Earnings (loss) per common share - basic (in dollars per share)	$ 0.38	$ 0.67	$ (0.14)	$ 0.72
Earnings (loss) per common share - diluted (in dollars per share)	$ 0.37	$ 0.66	$ (0.14)	$ 0.71
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares of stock options and other stock awards excluded from computation of earnings per share, amount (in shares)					1,200,000	0	1,700,000	100,000	1,800,000
Stated interest rate on debt instrument										4.25%	4.25%	4.25%
Conversion price (in dollars per share)										$ 22.45		$ 22.45