Costs and Estimated Earnings on Uncompleted Contracts - Reconciliation of Net Billings in Excess of Costs and Estimated Earnings (Detail) $ in Thousands	3 Months Ended
	Dec. 31, 2018 USD ($)
Costs and Estimated Earnings in Excess of Billings on Uncompleted Contracts
Contract asset, beginning balance	$ 9,334
Changes in revenue billed, contract price or cost estimates	858
Contract asset, ending balance	10,192
Billings in Excess of Costs and Estimated Earnings on Uncompleted Contracts
Contract liability, beginning balance	(38,738)
Changes in revenue billed, contract price or cost estimates	(733)
Contract liability, ending balance	(39,471)
Net Billings in Excess of Costs and Estimated Earnings on Uncompleted Contracts
Net billings in excess of costs, beginning balance	(29,404)
Changes in revenue billed, contract price or cost estimates	125
Net billings in excess of costs, Ending balance	$ (29,279)