Debt - Interest Rate Swap Contracts as Reflected on Balance Sheet (Details) - Designated as Hedging Instrument - Interest Rate Swaps - USD ($) $ in Thousands	Jun. 30, 2021	Sep. 30, 2020
Derivatives, Fair Value [Line Items]
Total derivatives	$ (2,982)	$ (7,792)
Current Liabilities: Other Current Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	(2,411)	(3,164)
Long-Term Liabilities: Other Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	$ (571)	$ (4,628)

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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