Financial Instruments (Schedule of Long-Term Debt) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt	$ 418,012	$ 424,029
Less: current portion	(12)	(20)
Long-term debt	418,000	424,009
Line of Credit [Member]
Debt Instrument [Line Items]
Long-term debt	$ 418,000	$ 424,000
Interest rate	3.17%	3.43%
Maturity date range, end	Dec. 31, 2022
Long-term Debt [Member]
Debt Instrument [Line Items]
Long-term debt	$ 12	$ 29
Interest rate	5.50%	5.50%
Maturity date range, end	Dec. 31, 2021

Contractual interest rate for funds borrowed, under the debt agreement.

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Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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- Definition

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.

+ References

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

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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