Fair Value Measurements (Gross Amounts and Fair Value of Debt) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross value	$ 1,014,740	$ 1,006,493
6.75% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross value	500,000	500,000
Fair value - Level 2 | 6.75% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities	463,750	533,250
Term Loan Due 2026 | Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross value	470,724,000,000	523,688
Term Loan Due 2026 | Fair value - Level 2 | Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities	$ 444,834	$ 528,684