Lines of Credit and Financing Arrangements (Outstanding Debt Obligations) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Commercial paper	$ 157.0	$ 0.0
Current maturities of long-term debt:
Finance lease obligations	16.9	14.9
Debt issuance costs	0.0	(0.4)
Total current maturities of long-term debt	16.9	314.5
Long-Term Debt:
Finance lease obligations	44.7	39.5
Debt issuance costs	(6.5)	(6.4)
Total long-term debt	838.2	833.1
Total debt	1,012.1	1,147.6
Senior Unsecured Notes
Current maturities of long-term debt:
Senior unsecured notes	0.0	300.0
Long-Term Debt:
Domestic credit facility and senior unsecured notes	$ 800.0	$ 800.0