Financing (Components Of Debt) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Total short-term borrowings	$ 30.2	$ 4.6
Other deferred financing costs associated with credit facilities	(3.0)	(3.4)
Total long-term debt	639.6	640.3
Debt discounts and debt issuance costs	$ 9.5	10.1
6.55% notes due November 2036
Debt Instrument [Line Items]
Debt instrument, interest rate	6.55%
Long-term debt	$ 198.6	198.6
4.20% notes due March 2048
Debt Instrument [Line Items]
Debt instrument, interest rate	4.20%
Long-term debt	$ 346.6	346.6
Term Facility | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Long-term debt	97.4	98.5
Term Facility | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Total short-term borrowings	5.2	4.6
Revolving Facility | Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Total short-term borrowings	$ 25.0	$ 0.0