Stockholders' Equity (Details 3) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Net Income (Loss) per Share of Common Stock
Net income (loss)	$ 105,189	$ 6,999	$ 2,283	$ 66,553	$ (8,320)	$ 13,722	$ (1,845)	$ 254,585	$ 9,915	$ (134,709)	$ 2,902	$ (63,452)	$ 181,024		$ 258,142		$ (185,344)
Weighted average shares outstanding, basic													23,459,432		22,660,429		22,371,264
Warrants and options outstanding for the purchase of common stock													1,293,512	[1]	1,289,996	[1]
Weighted average shares outstanding, diluted													24,752,944		23,950,425		22,371,264
Basic EPS	$ 4.22	$ 0.30	$ 0.10	$ 2.91	$ (0.37)	$ 0.60	$ (0.08)	$ 11.35	$ 0.44	$ (6.02)	$ 0.13	$ (2.84)	$ 7.72		$ 11.39		$ (8.28)
Diluted EPS	$ 4.06	$ 0.28	$ 0.09	$ 2.74	$ (0.37)	$ 0.57	$ (0.08)	$ 11.04	$ 0.44	$ (6.02)	$ 0.13	$ (2.84)	$ 7.31		$ 10.78		$ (8.28)

[1] As of December 31, 2010, Diluted EPS excludes 3.5 million warrants and 12,000 options which were not dilutive for the period. On November 8, 2012, all of our outstanding warrants were exercised. We issued 1,690,466 shares of our class A common stock pursuant to the terms of the warrants, and no longer have any warrants outstanding as of December 31, 2012.