Financing (Components Of Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Feb. 05, 2018	Nov. 30, 2006
Debt Instrument [Line Items]
Total short-term borrowings	$ 210.0	$ 4.6
Other deferred financing costs associated with credit facilities	(4.9)	(3.4)
Total long-term debt	540.6	640.3
Debt discounts and debt issuance costs	$ 9.4	$ 10.1
6.55% notes due November 2036 | Senior Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	6.55%	6.55%		6.55%
Long-term debt	$ 198.7	$ 198.6
4.20% notes due March 2048 | Senior Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	4.20%	4.20%	4.20%
Long-term debt	$ 346.8	$ 346.6
Term Facility | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Long-term debt	0.0	98.5
Term Facility | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Total short-term borrowings	0.0	4.6
Revolving Credit Facility | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Total short-term borrowings	$ 210.0	$ 0.0