Contract Assets and Liabilities - Contract Assets Reflect Costs and Estimated Earnings in Excess of Billings on Uncompleted Contracts (Detail) - USD ($)	Dec. 31, 2025	Sep. 30, 2025
Contract with Customer, Asset, after Allowance for Credit Loss [Abstract]
Costs incurred on uncompleted contracts	$ 9,210,000	$ 17,360,000
Estimated earnings	3,157,000	5,926,000
Costs and estimated earnings on uncompleted contracts	12,367,000	23,286,000
Billings to date	7,276,000	11,078,000
Contract assets	$ 5,091,000	$ 12,208,000