Restatement of Previously Issued Financial Statements - Balance Sheets (Details) - USD ($) $ in Thousands	Aug. 31, 2017	Feb. 28, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories - net	$ 108,453
Costs and estimated earnings in excess of billings on uncompleted contracts	65,818	$ 50,262
Total current assets	323,188	297,052
Total assets	1,009,582	978,354
Other accrued liabilities	21,590	24,042
Customer deposits	1,606	1,459
Billings in excess of costs and estimated earnings on uncompleted contracts	21,687	20,617
Total current liabilities	118,412	136,770
Deferred income tax liabilities	54,559	53,648
Total liabilities	460,493	445,218
Retained earnings	511,530	498,527
Total shareholders’ equity	549,089	533,136
Total liabilities and shareholders' equity	1,009,582	$ 978,354
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories - net	144,008
Costs and estimated earnings in excess of billings on uncompleted contracts	32,082
Total current assets	325,007
Total assets	1,011,401
Other accrued liabilities	20,085
Customer deposits	25,951
Billings in excess of costs and estimated earnings on uncompleted contracts	6,708
Total current liabilities	126,273
Deferred income tax liabilities	52,293
Total liabilities	466,088
Retained earnings	507,754
Total shareholders’ equity	545,313
Total liabilities and shareholders' equity	1,011,401
Correction
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories - net	(35,555)
Costs and estimated earnings in excess of billings on uncompleted contracts	33,736
Total current assets	(1,819)
Total assets	(1,819)
Other accrued liabilities	1,505
Customer deposits	(24,345)
Billings in excess of costs and estimated earnings on uncompleted contracts	14,979
Total current liabilities	(7,861)
Deferred income tax liabilities	2,266
Total liabilities	(5,595)
Retained earnings	3,776
Total shareholders’ equity	3,776
Total liabilities and shareholders' equity	$ (1,819)