Long-Term Indebtedness (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Unamortized deferred financing fees	$ (11,759)	$ (1,291)
Long-term debt	1,086,389	738,249
Less current portion	(74,311)	(17,831)
Long-term debt, excluding current maturities	1,012,078	720,418
Convertible Notes
Debt Instrument [Line Items]
Long-term debt, gross	460,000	0
Term Loan
Debt Instrument [Line Items]
Long-term debt, gross	273,750	285,000
Line of Credit
Debt Instrument [Line Items]
Long-term debt, gross	305,074	394,888
Shelf Loan
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
Other
Debt Instrument [Line Items]
Long-term debt, gross	$ 9,324	$ 9,652

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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