Summary of Significant Accounting Policies - Schedule of Earnings Per Share, Basic and Diluted (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Basic EPS:
Net income (loss)	$ (59,327)	$ 57,572
Weighted average common shares outstanding (in shares)	50,904	50,254
Basic (in dollars per share)	$ (1.17)	$ 1.15
Diluted EPS:
Net income (loss)	$ (59,327)	$ 57,572
Weighted average common shares outstanding (in shares)	50,904	50,254
Dilutive effect of stock awards (in shares)	0	9
Weighted average diluted shares outstanding	50,904	50,263
Diluted (in dollars per share)	$ (1.17)	$ 1.15