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Leases and Commitments - Schedule of Operating Lease Cost (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
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Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Commitments And Contingencies Disclosure [Abstract] |  |  |  |
Operating lease cost | $ 15,634 | $ 18,094 | $ 51,000 | $ 55,897
Change in operating lease cost | $ (2,460) |  | $ (4,897) |
Percentage of change in operating lease cost | (13.60%) |  | (8.80%) |

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- Definition Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980 + Details
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