Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statements of Comprehensive Income (Loss) [Abstract]
Net income (loss)	$ 58,026	$ (239,256)	$ (53,870)
Other comprehensive income (loss):
Realized loss (gain) on hedge derivative contract settlements reclassified into earnings from other comprehensive income (loss), net of taxes	(82,196)	(39,931)	(127,965)
Change in unrealized deferred hedging gains (losses), net of taxes	171,353	100,980	56,879
Total comprehensive income (loss)	$ 147,183	$ (178,207)	$ (124,956)