Revenue Recognition and Related Costs - Additional Information (Detail) - USD ($)	3 Months Ended
	Dec. 31, 2019	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Amortization period for incremental costs	1 year
Costs and estimated earnings in excess of billings	$ 13,383,000	$ 13,838,000
Accounts receivable related to contracts with customers	301,000	325,000
Current Liabilities [Member]
Disaggregation of Revenue [Line Items]
Customer deposits related to contracts with customers	$ 4,921,000	$ 1,918,000
Maximum [Member]
Disaggregation of Revenue [Line Items]
Contract assets collection period	1 year