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Investments in Marketable Securities - Debt Securities, Available-for-Sale (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Available-for-Sale
Cost	$ 252.3	$ 0.0
Unrealized losses	(1.3)	0.0
Fair value	251.0	0.0
Trading
Cost	19.7	14.1
Unrealized losses	(1.7)	(0.1)
Fair value	$ 18.0	$ 14.0

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Debt Securities, Trading, Accumulated Gross Unrealized Loss, Before Tax

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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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