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v3.20.2

401(k) Plan (Details) - USD ($) | 12 Months Ended
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Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2018
Retirement Benefits [Abstract] |  |  |
Employee contribution, percentage of annual salary | 100.00% |  |
Employee contribution, maximum allowable contribution | $ 56,000 |  |
Service period for participation eligibility | 30 days |  |
Service period for eligibility of profit sharing or matching contributions | 1 year |  |
Employer matching contribution percent | 100.00% |  |
Percent of employees' gross pay | 4.00% |  |
Profit sharing contribution, vesting schedule (in years) | 6 years |  |
Profit sharing contribution, percent | 7.00% |  |
Company contributions to plan | $ 8,333,000 | $ 6,920,000 | $ 5,910,000

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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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