Annual report pursuant to Section 13 and 15(d)

Revenue Recognition - Additional Information (Detail)

v3.19.1
Revenue Recognition - Additional Information (Detail) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2017
Apr. 01, 2018
Contract With Customer Assets And Liabilities [Line Items]                        
Net sales $ 23,641,000 $ 17,198,000 $ 21,441,000 $ 29,551,000 $ 22,178,000 $ 17,281,000 $ 17,224,000 $ 20,851,000 $ 91,831,000 $ 77,534,000 $ 91,769,000  
Percentage of revenue from contracts recognized over time                 60.00%      
Percentage of revenue from contracts recognized upon shipment                 40.00%      
Revenue recognized included in contract liability                 $ 10,680,000      
Unbilled revenue                 1,430,000      
Contract with customer liability increase in contract asset due to contract progress.                 7,626,000      
Contract with customer liability offset by invoicing to customers.                 5,894,000      
Customer deposits, current                 4,262,000      
Contract with customer liability offset by new customer deposits. 16,875,000               16,875,000      
Receivables billed but not paid under retainage provisions in its customer contracts 2,214,000       $ 1,124,000       2,214,000 1,124,000    
Amortization expense                 168,000      
Revenue remaining unsatisfied performance obligations amount 132,127,000               132,127,000      
Revenue remaining performance obligation held for sale 8,039,000               8,039,000      
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]                        
Contract With Customer Assets And Liabilities [Line Items]                        
Unbilled revenue 302,000               302,000      
Customer deposits 1,933,000               1,933,000      
Customer Deposit [Member]                        
Contract With Customer Assets And Liabilities [Line Items]                        
Contract liabilities 6,382,000               6,382,000     $ 2,220,000
Prepaid Expenses and Other Current Assets [Member]                        
Contract With Customer Assets And Liabilities [Line Items]                        
Capitalized costs, net of amortization $ 133,000               133,000     $ 118,000
Sudan [Member]                        
Contract With Customer Assets And Liabilities [Line Items]                        
Net sales                 0 0 0  
Iran [Member]                        
Contract With Customer Assets And Liabilities [Line Items]                        
Net sales                 0 0 0  
Syria [Member]                        
Contract With Customer Assets And Liabilities [Line Items]                        
Net sales                 $ 0 $ 0 $ 0