Financial Instruments and Risk Management (Schedule of Available-for-sale Securities Reconciliation) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 38.0	$ 38.1
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0.0	0.1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(2.7)	0.0
Fair Value	35.3	38.2
Available-for-sale fixed income investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	38.0	38.1
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0.0	0.1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(2.7)	0.0
Fair Value	$ 35.3	$ 38.2

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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