Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Components of the provision for income taxes
Federal	$ 0	$ 0	$ 0	$ 0
State	246	(132)	348	261
Deferred portion of income tax expense	(45,959)	(14,927)	(56,239)	(30,215)
Income tax expense	$ (46,205)	$ (14,795)	$ (56,587)	$ (30,476)
Effective tax rate	37.60%	37.30%	37.80%	37.30%