Fair Value Measurements (Gross Amounts and Fair Value of Debt) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross value	$ 1,096,406	$ 1,243,299
Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross value	603,738	1,243,299
6.75% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross value	500,000
Fair value - Level 2 | Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities	603,134	$ 1,182,688
Fair value - Level 2 | 6.75% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities	$ 498,125