Fair Value Measurements (Gross Amounts and Fair Value of Debt) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 26, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross value	$ 818,246	$ 967,661
Term Loan Due 2026
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross value	356,240	469,411
6.75% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross value	$ 449,695	$ 452,836
6.75% Senior Notes | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated rate	6.75%	6.75%
Fair value - Level 2 | Term Loan Due 2026
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value	$ 357,131	$ 460,023
Fair value - Level 2 | 6.75% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value	$ 469,931	$ 464,157
6.75% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated rate	0.0675%	0.0675%
6.75% Senior Notes | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated rate	6.75%		6.75%