Fair Value Measurements (Gross Amounts and Fair Value of Debt) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Term loan | Successor Company
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities	$ 1,296,750
Term loan | Predecessor Company
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities		$ 1,722,209
7.75% senior notes | Predecessor Company
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities		610,000
Fair value - Level 2 | Term loan | Successor Company
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities	$ 1,281,319
Fair value - Level 2 | Term loan | Predecessor Company
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities		1,481,100
Fair value - Level 2 | 7.75% senior notes | Predecessor Company
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities		$ 105,988