Investments - Gains and Losses on Investments within Change in Fair Value (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Net gain on equity securities (level 1)	$ 141.0	$ 14.4
Equity method loss on Other investments	(0.4)	(6.8)
Change in fair value of investments	140.6	7.6
Change in fair value of investments	$ 107.1	$ 14.4

Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount of realized and unrealized gain (loss) on investment.

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Amount of income (loss) for proportionate share of equity method investee's income (loss).

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