Financial Instruments and Fair Value Measurements (Assets Measured on a Nonrecurring Basis) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Apr. 30, 2025	Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain/(Loss) on goodwill	$ 0.0		$ 0.0	$ (65.3)	$ 0.0
Gain/(Loss) on franchise rights	0.0		0.0	(71.7)	0.0
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain/(Loss) on equity investment				0.0	(8.4)
Gain/(Loss) on goodwill				(65.3)	0.0
Gain/(Loss) on assets held and used				(4.3)	(8.9)
Gain/(Loss) on assets held for sale				(2.4)	(1.3)
Fair Value, Nonrecurring [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investment	0.0		48.3	0.0	48.3
Goodwill	75.2		0.0	75.2	0.0
Long-lived assets held and used	13.5		0.0	13.5	0.0
Long-lived assets held for sale	22.7		12.1	22.7	12.1
Franchise Rights | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain/(Loss) on franchise rights		$ (71.7)		(71.7)	0.0
Franchise Rights | Fair Value, Nonrecurring [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Franchise rights	42.7		$ 0.0	42.7	$ 0.0
Franchise Rights | Fair Value, Nonrecurring [Member] | Level 3 | Valuation Technique, Discounted Cash Flow [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Franchise rights						$ 42.7
Carrying value | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investment	$ 50.5			$ 50.5			$ 49.8