Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Components of the provision for income taxes
Federal	$ 0	$ 0	$ 0	$ 0
State	(46)	174	302	435
Deferred portion of income tax expense	(42,380)	22,910	(98,619)	(7,305)
Income tax (expense) benefit	$ (42,334)	$ 22,736	$ (98,921)	$ (7,740)
Effective tax rate	37.50%	37.20%	37.60%	37.50%