Financing Arrangements - Long-term debt (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Financing Arrangements
Total debt	$ 200.0	$ 310.0
Less debt issuance costs (deduction from liability)	(1.8)	(0.8)
Less current maturities		(105.0)
Total long-term debt	198.2	$ 204.2
Principal payments during each of the next five years and thereafter
2021	0.0
2022	200.0
5.05% Senior notes due 2020
Financing Arrangements
Interest rate (as a percent)		5.05%
Total debt		$ 75.0
Term Loan due February 2021
Financing Arrangements
Total debt		225.0
Line of Credit matures February 2021
Financing Arrangements
Total debt		10.0
Line of Credit matures February 2022
Financing Arrangements
Total debt	$ 200.0
Letters of credit
Financing Arrangements
Term of letters of credit from the date of issuance	1 year
Principal payments during each of the next five years and thereafter
Letters of credit outstanding	$ 16.2	$ 25.8

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

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