Other Items - Accounts Receivable, Net (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2024 |
Sep. 30, 2023 |
|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | |||
| Allowance for credit losses | $ (9,772) | $ (4,791) | |
| Accounts receivable, net | 898,095 | 879,514 | |
| Accounts Receivable, Allowance for Credit Loss [Roll Forward] | |||
| Balance at beginning of period | 4,791 | 3,719 | $ 8,273 |
| Provision for estimated credit losses | 8,980 | 12,761 | 7,097 |
| Write-offs, net of recoveries | (3,999) | (11,689) | (11,651) |
| Balance at end of period | 9,772 | 4,791 | $ 3,719 |
| Billed and billable receivables | |||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | |||
| Accounts Receivable Gross | 720,495 | 734,817 | |
| Unbilled receivables | |||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | |||
| Accounts Receivable Gross | $ 187,372 | $ 149,488 | |
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of allowance for credit loss on accounts receivable. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of allowance for credit loss on accounts receivable, classified as current. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of increase in allowance for credit loss on accounts receivable, from recovery. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available.
|
| X | ||||||||||
- Definition Amount of direct write-downs of accounts receivable charged against the allowance. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|