Fair Value (Fair Value of Assets and Liabilities Measured on Recurring Basis) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Level 1 [Member]
Total Assets	$ 0.4	$ 0.4
Total Liabilities	0.0	0.0
Level 1 [Member] \| Subsidiaries [Member]
Total Assets	0.4	0.4
Total Liabilities	0.0	0.0
Level 2 [Member]
Total Assets	8.0	9.0
Total Liabilities	1,386.6	1,502.5
Level 2 [Member] \| Subsidiaries [Member]
Total Assets	8.0	9.0
Total Liabilities	565.7	625.4
Level 3 [Member]
Total Assets	0.0	0.0
Total Liabilities	17.1	17.2
Level 3 [Member] \| Subsidiaries [Member]
Total Assets	0.0	0.0
Total Liabilities	17.1	17.2
Fair Value [Member]
Total Assets	8.4	9.4
Total Liabilities	1,403.7	1,519.7
Fair Value [Member] \| Subsidiaries [Member]
Total Assets	8.4	9.4
Total Liabilities	582.8	642.6
Money Market Funds [Member] \| Level 1 [Member]
Investments, Fair Value Disclosure	0.4	0.4
Money Market Funds [Member] \| Level 1 [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	0.4	0.4
Money Market Funds [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	0.0	0.0
Money Market Funds [Member] \| Level 2 [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	0.0	0.0
Money Market Funds [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure	0.0	0.0
Money Market Funds [Member] \| Level 3 [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	0.0	0.0
Money Market Funds [Member] \| Fair Value [Member]
Investments, Fair Value Disclosure	0.4	0.4
Money Market Funds [Member] \| Fair Value [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	0.4	0.4
Equity Securities [Member] \| Level 1 [Member]
Investments, Fair Value Disclosure	0.0	0.0
Equity Securities [Member] \| Level 1 [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	0.0	0.0
Equity Securities [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	4.5	5.1
Equity Securities [Member] \| Level 2 [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	4.5	5.1
Equity Securities [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure	0.0	0.0
Equity Securities [Member] \| Level 3 [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	0.0	0.0
Equity Securities [Member] \| Fair Value [Member]
Investments, Fair Value Disclosure	4.5	5.1
Equity Securities [Member] \| Fair Value [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	4.5	5.1
Debt Securities [Member] \| Level 1 [Member]
Investments, Fair Value Disclosure	0.0	0.0
Debt Securities [Member] \| Level 1 [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	0.0	0.0
Debt Securities [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	3.5	3.9
Debt Securities [Member] \| Level 2 [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	3.5	3.9
Debt Securities [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure	0.0	0.0
Debt Securities [Member] \| Level 3 [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	0.0	0.0
Debt Securities [Member] \| Fair Value [Member]
Investments, Fair Value Disclosure	3.5	3.9
Debt Securities [Member] \| Fair Value [Member] \| Subsidiaries [Member]
Investments, Fair Value Disclosure	3.5	3.9
Debt [Member] \| Level 1 [Member]
Debt	0.0	0.0
Debt [Member] \| Level 1 [Member] \| Subsidiaries [Member]
Debt	0.0	0.0
Debt [Member] \| Level 2 [Member]
Debt	1,386.6	1,502.5
Debt [Member] \| Level 2 [Member] \| Subsidiaries [Member]
Debt	565.7	625.4
Debt [Member] \| Level 3 [Member]
Debt	17.1	17.2
Debt [Member] \| Level 3 [Member] \| Subsidiaries [Member]
Debt	17.1	17.2
Debt [Member] \| Fair Value [Member]
Debt	1,403.7	1,519.7
Debt [Member] \| Fair Value [Member] \| Subsidiaries [Member]
Debt	$ 582.8	$ 642.6

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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Fair value of financial and nonfinancial obligations.

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