Costs and Estimated Earnings in Excess of Billings - Costs and Estimated Earnings in Excess of Billings on Uncompleted Contracts (Detail) - USD ($)	Sep. 30, 2020	Sep. 30, 2019
Costs in Excess of Billings on Uncompleted Contracts or Programs [Abstract]
Costs incurred on uncompleted contracts	$ 10,390,000	$ 18,707,000
Estimated earnings	4,680,000	9,063,000
Costs and estimated earnings on uncompleted contracts	15,070,000	27,770,000
Billings to date	8,665,000	13,932,000
Costs and estimated earnings in excess of billings	$ 6,405,000	$ 13,838,000