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Employee Benefits Plans - Narrative (Details) - USD ($) | 1 Months Ended | 12 Months Ended
--- | --- | ---
Aug. 31, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019
Compensation And Retirement Disclosure [Abstract] |  |  |  |
Benefit plan period |  | 180 months |  |
Weighted-average discount rate |  |  |  | 4.08%
MSP termination benefits payment | $ 5,175,000 |  | $ 5,175,000 |
Additional liability recorded |  |  |  | $ 720,000
Matching contribution (as a percent) (up to) |  | 4.00% |  |
Contribution to plan |  | $ 401,000 | 397,000 | 380,000
Contribution to profit sharing plan |  | $ 0 | $ 0 | $ 0

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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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- Definition Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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