DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Research and development costs, shipping and handling costs and advertising costs (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Research and development arrangement, contract to perform for others, costs incurred, gross	$ 16,312	$ 15,884	$ 14,076
Shipping and handling cost	79,097	81,378	80,004
Selling, general and administrative expenses	430,622	436,163	446,798
Shipping and Handling
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Selling, general and administrative expenses	67,500	68,400	67,300
Advertising
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Selling, general and administrative expenses	$ 26,000	$ 23,500	$ 25,700

- Definition

The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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