Income Taxes - Income Tax Expense (Benefit) Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Tax at the statutory federal rate	$ 182,700	$ 1,603	$ 2,240
State income taxes (net of federal benefit)	18,270	160	224
Decrease in valuation allowance	(86,882)	(2,218)	(2,870)
Other	1,419	46	793
Total income tax expense (benefit)	$ 115,507	$ (409)	$ 387