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Debt and Credit Agreements - Schedule of Debt (Details) - USD ($) $ in Thousands	1 Months Ended
	Jul. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Unamortized debt issuance costs		$ (3,288)	$ (3,975)
Long-term debt		1,161,712	1,220,025
Current portion of long-term debt		$ 188,000	87,000
6.51% weighted-average senior notes
Debt Instrument [Line Items]
Weighted average interest rate		6.51%
Total debt		$ 37,000	124,000
Debt repaid	$ 87,000
5.58% weighted-average senior notes
Debt Instrument [Line Items]
Weighted average interest rate		5.58%
Total debt		$ 175,000	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
Revolving credit facility
Debt Instrument [Line Items]
Total debt		$ 28,000	$ 0