Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025	Sep. 30, 2024
Supplemental disclosure of non-cash activity:
Increase in operating lease right-of-use assets	$ 1,123	$ 594
Increase in operating lease liabilities	1,123	594
Supplemental disclosure of cash activity:
Interest payments	39,357	39,414
Income tax payments	2,600	6,606
Reconciliation of cash, cash equivalents, and restricted cash:
Cash and cash equivalents	116,440	85,082	$ 214,705
Restricted cash	3,961	23,386	3,866
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	$ 120,401	$ 108,468	$ 218,571	$ 242,610

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Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

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Amount of cash and cash equivalent, and cash and cash equivalent restricted to withdrawal or usage; attributable to continuing operation. Cash includes, but is not limited to, currency on hand, demand deposit with financial institution, and account with general characteristic of demand deposit. Cash equivalent includes, but is not limited to, short-term, highly liquid investment that is both readily convertible to known amount of cash and so near maturity that it presents insignificant risk of change in value because of change in interest rate.

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Amount, before refund, of cash paid to foreign, federal, state, and local jurisdictions as income tax.

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Amount of cash paid for interest, excluding capitalized interest, classified as operating activity. Includes, but is not limited to, payment to settle zero-coupon bond for accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount.

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