Goodwill and Intangible Assets (Summary Of Intangible Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period of Finite Lived Assets (in years)	18 years
Gross Asset	$ 657.8	$ 666.4
Accumulated Amortization	360.8	357.5
Net	$ 297.0	308.9	$ 344.9
Intellectual property rights
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period of Finite Lived Assets (in years)	12 years 6 months
Gross Asset	$ 62.0	62.2
Accumulated Amortization	14.9	15.0
Net	$ 47.1	47.2
Customer relationships and backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period of Finite Lived Assets (in years)	18 years 9 months 18 days
Gross Asset	$ 497.1	504.4
Accumulated Amortization	271.5	269.5
Net	$ 225.6	234.9
Other
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period of Finite Lived Assets (in years)	10 years
Gross Asset	$ 98.7	99.8
Accumulated Amortization	74.4	73.0
Net	$ 24.3	$ 26.8