Fair Value Measurements - Carrying Values and Estimated Fair Values of Financial Instruments (Details) - Level 2 - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Carrying Amount
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total long-term debt	$ 2,230,563	$ 2,175,000
Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total long-term debt	1,829,577	2,181,750
Term Loan, Secured Due April 2024 \| Carrying Amount
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Term loan	972,563	975,000
Term Loan, Secured Due April 2024 \| Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Term loan	889,895	975,000
6.875% Notes, Unsecured, Due April 2022, Issued 2017 \| Carrying Amount
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes payable	700,000	700,000
6.875% Notes, Unsecured, Due April 2022, Issued 2017 \| Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes payable	530,432	701,750
7.125% Notes, Unsecured, Due April 2025, Issued 2017 \| Carrying Amount
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes payable	500,000	500,000
7.125% Notes, Unsecured, Due April 2025, Issued 2017 \| Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes payable	351,250	$ 505,000
Credit Facility Secured Due January 2022 \| Carrying Amount
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Credit facility	58,000
Credit Facility Secured Due January 2022 \| Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Credit facility	$ 58,000

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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- Definition

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.

+ 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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