Financial Instruments and Fair Value Measurements (Summary Of Carrying Values and Fair Values Of Fixed Rate Debt) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity investments with readily determinable fair values	$ 9.9		$ 20.0
Net losses recognized during the period on equity securities	(10.1)	$ (8.5)
Less: Net gains (losses) recognized during the period on equity securities sold during the period	0.0	0.0
Unrealized losses recognized during the reporting period on equity securities still held at the reporting date	(10.1)	(8.5)
Carrying value | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed rate debt	3,280.0		2,782.1
Fair value | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed rate debt	3,192.9		2,578.6
Fair Value, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities without readily determinable fair value, downward adjustment	0.0	8.4
Equity investment without readily determinable fair value, cumulative downward adjustment	8.4
Equity investment without readily determinable fair value, cumulative upward adjustment	3.4
Fair Value, Nonrecurring [Member] | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity investment without readily determinable fair value	0.0	$ 48.3
Fair Value, Nonrecurring [Member] | Carrying value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity investment without readily determinable fair value	$ 50.5		$ 49.8