Financing (Components Of Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Total short-term borrowings	$ 155.0	$ 4.6
Other deferred financing costs associated with credit facilities	(2.6)	(3.4)
Total long-term debt	638.2	640.3
Debt discounts and debt issuance costs	$ 8.5	10.1
6.55% notes due November 2036
Debt Instrument [Line Items]
Debt instrument, interest rate	6.55%
Long-term debt	$ 198.7	198.6
4.20% notes due March 2048
Debt Instrument [Line Items]
Debt instrument, interest rate	4.20%
Long-term debt	$ 346.7	346.6
Term Facility | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Long-term debt	95.4	98.5
Term Facility | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Total short-term borrowings	5.0	4.6
Revolving Facility | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Total short-term borrowings	$ 150.0	$ 0.0