Income Taxes (Details) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2013	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Income Taxes
Net deferred tax liability	$ 55,400			$ 55,400		$ 38,300
Increase to income tax provision	$ 16,221	$ 20,111		$ 26,636	$ 22,112
Effective tax rate (as a percent)	84.46%			84.59%
Increase in effective tax rate due to increase in valuation allowance (as a percent)	43			43
Restatement adjustment
Income Taxes
Increase to income tax provision	$ 5,067	11,357		$ 6,222	6,558
Correction of failed spin-off leaseback accounting treatment
Income Taxes
Period of cumulative pre-tax loss position			3 years
Increase to income tax provision	$ 8,000	$ 16,500		$ 13,100	$ 16,700