Fair Value Measurements (Assets and Liabilities Measured on a Recurring and Nonrecurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	$ 8.3	$ 8.0
Debt Instrument, Fair Value Disclosure	1,700.7	1,709.0
Money Market Funds [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Master Trust Assets, Fair Value	0.8	0.4
Mutual Fund | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Master Trust Assets, Fair Value	7.5	7.6
Debt [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	1,798.3	1,840.0
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	8.3	8.0
Debt Instrument, Fair Value Disclosure	0.0	0.0
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Master Trust Assets, Fair Value	0.8	0.4
Fair Value, Inputs, Level 1 [Member] | Mutual Fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Master Trust Assets, Fair Value	7.5	7.6
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	0.0	0.0
Debt Instrument, Fair Value Disclosure	1,684.3	1,692.4
Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Master Trust Assets, Fair Value	0.0	0.0
Fair Value, Inputs, Level 2 [Member] | Mutual Fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Master Trust Assets, Fair Value	0.0	0.0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	0.0	0.0
Debt Instrument, Fair Value Disclosure	16.4	16.6
Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Master Trust Assets, Fair Value	0.0	0.0
Fair Value, Inputs, Level 3 [Member] | Mutual Fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Master Trust Assets, Fair Value	$ 0.0	$ 0.0