Long Term Debt - Summary of Debt Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Principal repayment obligation	$ 1,985,758	$ 2,044,035
Unamortized DFC and discounts	(51,635)	(56,650)
Unamortized premium	225,085	228,096
Carrying value	2,159,208	2,215,481
Principal repayment obligation, Current Maturities	(9,750)	(7,313)
Carrying Value, Current maturities	(9,750)	(7,313)
Principal repayment obligation, Total long-term debt, net	1,976,008	2,036,722
Unamortized DFC and discounts, Total long-term debt, net	(51,635)	(56,650)
Unamortized premium, Total long-term debt, net	225,085	228,096
Total long-term debt, net	2,149,458	2,208,168
Credit Facility, Secured Due January 2022
Debt Instrument [Line Items]
Principal repayment obligation	59,000	104,000
Carrying value	59,000	104,000
Term Loan, Secured, Due April 2024
Debt Instrument [Line Items]
Principal repayment obligation	973,247	975,000
Unamortized DFC and discounts	(24,722)	(26,874)
Carrying value	948,525	948,126
Second Lien Notes, Secured, Due July 2024
Debt Instrument [Line Items]
Principal repayment obligation	578,072	545,000
Unamortized premium	225,085	228,096
Carrying value	803,157	773,096
6.875% Notes, Unsecured, Due April 2022
Debt Instrument [Line Items]
Principal repayment obligation	150,439	195,035
Unamortized DFC and discounts	(13,201)	(15,168)
Carrying value	137,238	179,867
7.125% Notes, Unsecured, Due April 2025
Debt Instrument [Line Items]
Principal repayment obligation	225,000	225,000
Unamortized DFC and discounts	(13,712)	(14,608)
Carrying value	$ 211,288	$ 210,392

Debt instrument carrying amount current.

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Debt instrument carrying amount noncurrent.

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Debt instrument unamortized discount and deferred financing costs, net.

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Debt instrument unamortized discount and deferred financing costs noncurrent net.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt premium.

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Amount of debt premium to be amortized after one year or the normal operating cycle, if longer.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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