Investments - Summary of Investments (Details) - USD ($) $ in Millions	Mar. 31, 2022	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Fixed income securities	$ 6.4	$ 0.6
Equity securities	1,138.7	1,267.6
Equity securities (other)	77.3	27.1
Other	56.6	68.8
Total investments	1,279.0	1,364.1
Less: Short-term Investments	(6.4)	(0.6)
Long-term investments	$ 1,272.6	$ 1,363.5

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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