Supporting Financial Information - Debt Obligations (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Net bank debt obligations	$ 46,750
Less: current portion of bank debt obligations, net of deferred financing costs	0	$ (6,727)
Long-term portion of bank debt obligations, net of deferred financing costs	44,636	60,544
Secured Debt
Debt Instrument [Line Items]
Bank term loan	46,750	70,000
Less: unamortized deferred financing costs	(2,114)	(2,729)
Net bank debt obligations	44,636	67,271
Less: current portion of bank debt obligations, net of deferred financing costs	0	(6,727)
Long-term portion of bank debt obligations, net of deferred financing costs	$ 44,636	$ 60,544

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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