Derivative Financial Instruments and Hedging Activities - Schedule of Fair Values of All Open Derivative Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Other Current Assets
Fair values of open derivative instruments
Fair value of derivative assets		$ 0.8
Other Current Liabilities
Fair values of open derivative instruments
Fair value of derivative liabilities	$ 2.5	0.4
Not Designated as Hedging Instruments | Foreign Exchange Contract | Other Current Assets
Fair values of open derivative instruments
Fair value of derivative assets		0.4
Not Designated as Hedging Instruments | Foreign Exchange Contract | Other Current Liabilities
Fair values of open derivative instruments
Fair value of derivative liabilities	2.0	0.4
Cash Flow Hedging | Designated as Hedging Instrument | Foreign Exchange Contract | Other Current Assets
Fair values of open derivative instruments
Fair value of derivative assets		$ 0.4
Cash Flow Hedging | Designated as Hedging Instrument | Foreign Exchange Contract | Other Current Liabilities
Fair values of open derivative instruments
Fair value of derivative liabilities	$ 0.5