Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Long-term debt	$ 600,397	$ 729,774
Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Senior secured notes	74,247	208,469
Unamortized debt issuance costs	(3,673)	(4,182)
Senior Secured Notes Due 2021 | Senior Notes
Line of Credit Facility [Line Items]
Senior secured notes	575,000	575,000
Unamortized debt issuance costs	$ (45,177)	$ (49,513)