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Costs and Estimated Earnings in Excess of Billings - Costs and Estimated Earnings in Excess of Billings on Uncompleted Contracts (Detail) - USD ($) | Sep. 30, 2021 | Sep. 30, 2020
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Costs in Excess of Billings on Uncompleted Contracts or Programs [Abstract] |  |
Costs incurred on uncompleted contracts | $ 11,483,000 | $ 10,390,000
Estimated earnings | 4,395,000 | 4,680,000
Costs and estimated earnings on uncompleted contracts | 15,878,000 | 15,070,000
Billings to date | 13,975,000 | 8,665,000
Costs and estimated earnings in excess of billings | $ 1,903,000 | $ 6,405,000

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