Debt and Credit Agreements - Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (2,877)	$ (3,076)
Long-term debt	1,046,123	1,133,924
Current portion of long-term debt	$ 100,000	188,000
6.51% weighted-average senior notes
Debt Instrument [Line Items]
Weighted average interest rate	6.51%
Total debt	$ 37,000	37,000
5.58% weighted-average senior notes
Debt Instrument [Line Items]
Weighted average interest rate	5.58%
Total debt	$ 87,000	175,000
Current portion of long-term debt	$ 88,000
3.65% weighted-average senior notes
Debt Instrument [Line Items]
Weighted average interest rate	3.65%
Total debt	$ 925,000	925,000
Current portion of long-term debt	$ 100,000	$ 100,000

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 accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Weighted average interest rate of long-term debt outstanding calculated at point in time.

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