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Major Clients (Details) - Sales Revenue - Customer concentration risk | 12 Months Ended
--- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2021
Percentage of total revenue |  |  |
Period for which criteria of threshold percentage for disclosure not met in past | 5 years |  |
Minimum |  |  |
Percentage of total revenue |  |  |
Percentage of revenue accounted for by no other single client (as a percent) | 10.00% |  |
Agencies of U.S. Federal Government |  |  |
Percentage of total revenue |  |  |
Concentration (as a percent) | 5.00% | 6.00% | 8.00%

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- 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. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 954 -SubTopic 310 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481027/954-310-50-2 + Details
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