Fair Value Measurements - Carrying Values and Estimated Fair Values of Financial Instruments (Details) - Level 2 - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Principal Repayment Obligation
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt	$ 1,963,656	$ 2,044,035
Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt	1,321,133	1,495,137
Credit Facility, Secured Due January 2022 \| Principal Repayment Obligation
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Credit facility	38,000	104,000
Credit Facility, Secured Due January 2022 \| Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Credit facility	38,000	104,000
Term Loan, Secured, Due April 2024 \| Principal Repayment Obligation
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Term loan	975,068	975,000
Term Loan, Secured, Due April 2024 \| Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Term loan	840,996	858,000
Second Lien Notes, Secured, Due July 2024 \| Principal Repayment Obligation
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes payable	575,149	545,000
Second Lien Notes, Secured, Due July 2024 \| Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes payable	342,616	395,125
6.875% Notes, Unsecured, Due April 2022 \| Principal Repayment Obligation
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes payable	150,439	195,035
6.875% Notes, Unsecured, Due April 2022 \| Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes payable	50,021	68,262
7.125% Notes, Unsecured, Due April 2025 \| Principal Repayment Obligation
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes payable	225,000	225,000
7.125% Notes, Unsecured, Due April 2025 \| Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes payable	$ 49,500	$ 69,750

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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+ References

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- Definition

Fair value portion of contractual arrangement with a lender under which borrowings can be made up to a specific amount at any point in time.

+ References

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- Definition

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+ References

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- Definition

Fair value portion of notes payable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20,22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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