Costs and Estimated Earnings in Excess of Billings - Costs and Estimated Earnings in Excess of Billings on Uncompleted Contracts (Detail) - USD ($)	Sep. 30, 2017	Sep. 30, 2016
Costs in Excess of Billings on Uncompleted Contracts or Programs [Abstract]
Costs incurred on uncompleted contracts	$ 10,250,000	$ 8,898,000
Estimated earnings	3,161,000	3,124,000
Costs and estimated earnings on uncompleted contracts	13,411,000	12,022,000
Costs and estimated earnings on uncompleted contracts	13,411,000	12,022,000
Billings to date	6,643,000	7,101,000
Costs and estimated earnings in excess of billings	$ 6,768,000	$ 4,921,000