Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current tax provision (benefit):
Federal		$ (1,600)	$ (11,309)
State	396	451	110
Total current payable	396	(1,149)	(11,199)
Deferred tax provision (benefit):
Federal	(21,533)	46,994	54,942
State	(1,698)	3,706	4,332
Total deferred payable	(23,231)	50,700	59,274
Provision (benefit) for income taxes	$ (22,835)	$ 49,551	$ 48,075