Fair Value Measurements (Financial Instruments Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading Securities at Fair Value	$ 104.2	$ 101.3
Investments, Fair Value Disclosure	11.6
Fair Value, Measurements, Recurring [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investments, Fair Value Disclosure	113.2	111.7
Total Assets at Fair Value	113.2	111.7
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 1 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investments, Fair Value Disclosure	113.2	111.7
Total Assets at Fair Value	113.2	111.7
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 2 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Total Assets at Fair Value	0.0	0.0
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Total Assets at Fair Value	0.0	0.0
Corporate Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable Securities	8.8	10.2
Corporate Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 1 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable Securities	8.8	10.2
Corporate Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 2 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable Securities	0.0	0.0
Corporate Debt Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable Securities	0.0	0.0
Mutual Fund [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading Securities at Fair Value	104.2	101.3
Mutual Fund [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 1 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading Securities at Fair Value	104.2	101.3
Mutual Fund [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 2 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading Securities at Fair Value	0.0	0.0
Mutual Fund [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading Securities at Fair Value	0.0
Equity Securities [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable Securities	0.2	0.2
Equity Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 1 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable Securities	0.2	0.2
Equity Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 2 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable Securities	0.0	0.0
Equity Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable Securities	$ 0.0	$ 0.0

Fair value portion of asset recognized for present right to economic benefit.

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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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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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