Lines of Credit and Financing Arrangements (Outstanding Debt Obligations) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Commercial paper	$ 150.0	$ 0.0
Current maturities of long-term debt:
Finance lease obligations	12.1	11.2
Senior unsecured notes	12.1	710.6
Long-Term Debt:
Finance lease obligations	32.7	28.3
Total long-term debt	1,143.1	814.2
Debt Issuance Cost, Gross, Noncurrent	(9.6)	(6.1)
Total debt	1,305.2	1,524.8
Domestic Credit Facility [Member]
Current maturities of long-term debt:
Debt issuance costs	0.0	(0.6)
Senior unsecured notes	0.0	350.0
Long-Term Debt:
Total long-term debt	20.0	192.0
Asset Securitization [Member]
Current maturities of long-term debt:
Asset securitization program	0.0	350.0
Senior Unsecured Notes [Member]
Long-Term Debt:
Total long-term debt	$ 1,100.0	$ 600.0