| Long-Term Debt | The components of our long-term debt are presented in the following tables (in thousands):  
|   | December 31, 2018 |   |   | December 31, 2017 |   |  
|   |   |   |   |   | Adjustments to |   |   |   |   |   |   |   |   |   |   | Adjustments to |   |   |   |   |   |  
|   |   |   |   |   | Carrying |   |   | Carrying |   |   |   |   |   |   | Carrying |   |   | Carrying |   |  
|   | Principal |   |   | Value (1) |   |   | Value |   |   | Principal |   |   | Value (2) |   |   | Value |   |  
| Credit Facility,       due October 2022 | $ | 21,000 |   |   | $ | — |   |   | $ | 21,000 |   |   | $ | — |   |   | $ | — |   |   | $ | — |   |  
|   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  
| 9.75 % Senior Second Lien Notes,     due November 2023: |   | 625,000 |   |   |   | (12,465 | ) |   |   | 612,535 |   |   |   | — |   |   |   | — |   |   |   | — |   |  
|   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  
| 11.00% 1.5 Lien Term Loan,     due November 2019: |   | — |   |   |   | — |   |   |   | — |   |   |   | 75,000 |   |   |   | 15,596 |   |   |   | 90,596 |   |  
|   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  
| 9.00 % Second Lien Term Loan,     due May 2020: |   | — |   |   |   | — |   |   |   | — |   |   |   | 300,000 |   |   |   | (4,381 | ) |   |   | 295,619 |   |  
|   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  
| 9.00%/10.75% Second Lien     PIK Toggle Notes, due May 2020: |   | — |   |   |   | — |   |   |   | — |   |   |   | 171,769 |   |   |   | 40,617 |   |   |   | 212,386 |   |  
|   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  
| 8.50%/10.00% Third Lien     PIK Toggle Notes, due June 2021: |   | — |   |   |   | — |   |   |   | — |   |   |   | 153,192 |   |   |   | 50,005 |   |   |   | 203,197 |   |  
|   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  
| 8.50% Unsecured Senior Notes,     due June 2019 |   | — |   |   |   | — |   |   |   | — |   |   |   | 189,829 |   |   |   | 425 |   |   |   | 190,254 |   |  
| Total long-term debt |   | 646,000 |   |   |   | (12,465 | ) |   |   | 633,535 |   |   |   | 889,790 |   |   |   | 102,262 |   |   |   | 992,052 |   |  
| Current maturities of long-term debt (3) |   | — |   |   |   | — |   |   |   | — |   |   |   | — |   |   |   | 22,925 |   |   |   | 22,925 |   |  
| Long term debt, less current     maturities | $ | 646,000 |   |   | $ | (12,465 | ) |   | $ | 633,535 |   |   | $ | 889,790 |   |   | $ | 79,337 |   |   | $ | 969,127 |   |    
|   | (1) | Unamortized debt issuance costs. |  
|   | (2) | Unamortized debt issuance costs, unamortized debt premiums, unamortized debt discounts, future interest payments for certain debt instruments and future payments-in-kind (“PIK”) for certain debt instruments recorded on an undiscounted basis. |  
|   | (3) | Future interest payments due within twelve months on the 1.5 Lien Term Loan, Second Lien PIK Toggle Notes and Third Lien PIK Toggle Notes (these debt instruments are defined below). |    |