Short-Term and Long-Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2024	Sep. 30, 2023
Debt Instrument [Line Items]
Current portion of long-term debt	$ 309.4	$ 8.6
Reported Value Measurement
Debt Instrument [Line Items]
Current portion of long-term debt	309.4	8.6
Long-term debt	2,584.5	2,862.9
Estimate of Fair Value Measurement
Debt Instrument [Line Items]
Current portion of long-term debt	302.9	8.6
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Long-term debt	$ 2,275.9	$ 2,442.6