Significant Accounting Policies - Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Equity securities, realized loss		$ 3.3	$ 5.2
Book value of cost method investment		$ 0.0	$ 0.0
Equity method investment, non-cash impairment	$ 1.1
Carrying value of equity method investment	$ 0.0