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Contract Revenue and Pass- Through and Other - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2018
Disaggregation Of Revenue [Line Items] |  |  |
Deferred revenue | $ 23,800 |  |
Deferred revenue, current | 9,389 | $ 1,513 |
Deferred revenue, noncurrent | 14,369 |  |
Lease revenue | 208,900 | 219,000 | $ 217,000
Contract Revenue [Member] |  |  |
Disaggregation Of Revenue [Line Items] |  |  |
Lease revenue | 208,900 | $ 219,000 |
Other Accrued Expenses [Member] |  |  |
Disaggregation Of Revenue [Line Items] |  |  |
Deferred revenue, current | $ 9,400 |  |

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- Definition Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(5)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable, classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(5)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable, classified as noncurrent. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(5)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919372-209981 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=121561866&loc=SL77919311-209978 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 50 -Paragraph 6A -URI http://asc.fasb.org/extlink&oid=121640914&loc=SL77927221-108306 + Details
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