Lines of Credit and Financing Arrangements (Outstanding Debt Obligations) (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Debt Instrument [Line Items]
Commercial paper	$ 412.0	$ 226.0
Current maturities of long-term debt:
Finance lease obligations	20.1	18.3
Total current maturities of long-term debt	20.1	18.3
Long-Term Debt:
Finance lease obligations	54.6	50.6
Debt issuance costs	(5.4)	(6.5)
Total long-term debt	1,149.2	1,144.1
Total debt	1,581.3	1,388.4
Senior Unsecured Notes
Long-Term Debt:
Domestic credit facility and senior unsecured notes	800.0	800.0
Domestic Credit Facility
Long-Term Debt:
Domestic credit facility and senior unsecured notes	$ 300.0	$ 300.0