Changes in Accumulated Other Comprehensive Loss (Classification Of Accumulated Other Comprehensive Income Reflected On Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 964.0	$ 783.8
Ending balance	964.1	964.0
Tax detriment	1.4	1.5
Pension and Postretirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	3.8
Other comprehensive loss before reclassifications	0.0
Amounts reclassified from accumulated other comprehensive loss	(0.4)
Net period other comprehensive loss	(0.4)
Ending balance	3.4	3.8
Currency Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(122.4)
Other comprehensive loss before reclassifications	(26.7)
Amounts reclassified from accumulated other comprehensive loss	0.0
Net period other comprehensive loss	(26.7)
Ending balance	(149.1)	(122.4)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(118.6)	(131.5)
Other comprehensive loss before reclassifications	(26.7)
Amounts reclassified from accumulated other comprehensive loss	(0.4)
Net period other comprehensive loss	(27.1)
Ending balance	$ (145.7)	$ (118.6)