Costs and Estimated Earnings in Excess of Billings - Costs and Estimated Earnings in Excess of Billings on Uncompleted Contracts (Detail) - USD ($)	Mar. 31, 2020	Sep. 30, 2019
Costs in Excess of Billings on Uncompleted Contracts or Programs [Abstract]
Costs incurred on uncompleted contracts	$ 17,950,000	$ 18,707,000
Estimated earnings	7,489,000	9,063,000
Costs and estimated earnings on uncompleted contracts	25,439,000	27,770,000
Billings to date	16,647,000	13,932,000
Costs and estimated earnings in excess of billings	$ 8,792,000	$ 13,838,000

Amount billed to customers under long-term contracts or programs to be collected in the next rolling twelve months following the latest balance sheet. Excludes amounts due that have been withheld because of retainage provisions in a contract. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

No definition available.

Name:	us-gaap_ContractReceivableDueInNextRollingTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant