Long-term Debt - Components of Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Principal	$ 709,481	$ 632,460
Unamortized debt issuance costs	(13,310)	(7,174)
Long-term Debt, Total	742,372	625,286
Less current portion	(46,201)
Total long-term debt, net	696,171	625,286
Term Loan [Member]
Principal	203,223
Unamortized debt issuance costs	(7,838)
Long-term Debt, Total	195,385
Less current portion	(46,200)
Credit Agreement [Member]
Long-term Debt, Total		80,000
Total long-term debt, net		80,000
Senior Second Lien Notes Due November 2023 [Member]
Principal	552,460	552,460
Unamortized debt issuance costs	(5,473)	(7,174)
Long-term Debt, Total	$ 546,987	$ 545,286

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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