Debt And Liquidity (Schedule Of Long-Term Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total debt	$ 1,273,123	$ 1,420,131
Less: Short-term debt	(127)	(131)
Long-term debt	1,272,996	1,420,000
Unamortized debt discount and issuance costs
Debt Instrument [Line Items]
Long-term Debt, Gross	591	615
2018 Credit Agreement
Debt Instrument [Line Items]
Long-term Debt, Gross	793,708	943,708
Secured Debt
Debt Instrument [Line Items]
Long-term Debt, Gross	500,000	500,000
Unamortized Financing Costs member
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ (21,176)	$ (24,192)

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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