Debt - Details of Long-term Debt Table - Total debt (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Debt Disclosure [Abstract]
Total	$ 1,813,168	$ 1,609,296
Plus: capital lease obligations	864	832
Less: unamortized debt issuance costs and discount, net	16,955	15,585
Total debt	$ 1,797,077	$ 1,594,543

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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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 of long-term debt and lease obligation, including portion classified as current.

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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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