Derivative Financial Instruments and Fair Value Measurements - Cash Flow Hedges (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Derivative financial instruments
Fixed Rate (as a percent)	1.349%
Interest rate swap agreements
Derivative financial instruments
Notional Amount	$ 400.0
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swap agreements | USD | March 2018
Derivative financial instruments
Notional Amount	$ 200.0	$ 200.0
Fixed Rate (as a percent)	2.60%	2.60%
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swap agreements | USD | February 2023
Derivative financial instruments
Notional Amount	$ 400.0
Fixed Rate (as a percent)	1.349%