Annual report pursuant to Section 13 and 15(d)

Revenue Recognition - Additional Information (Detail)

v3.20.1
Revenue Recognition - Additional Information (Detail) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2020
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2018
Apr. 01, 2018
Contract With Customer Assets And Liabilities [Line Items]                        
Net sales $ 23,082,000 $ 25,286,000 $ 21,643,000 $ 20,593,000 $ 23,641,000 $ 17,198,000 $ 21,441,000 $ 29,551,000 $ 90,604,000 $ 91,831,000 $ 77,534,000  
Percentage of revenue from contracts recognized over time                 70.00%      
Percentage of revenue from contracts recognized upon shipment                 30.00%      
Revenue recognized included in contract liability                 $ 17,040,000      
Unbilled revenue (contract assets)                 7,070,000      
Contract with customer liability increase in contract asset due to contract progress.                 20,585,000      
Contract with customer liability offset by invoicing to customers.                 13,515,000      
Customer deposits, current                 3,864,000      
Contract with customer liability offset by new customer deposits                 13,176,000      
Receivables billed but not paid under retainage provisions in its customer contracts 2,016,000       2,214,000       2,016,000 2,214,000    
Amortization expense                 169,000      
Revenue remaining unsatisfied performance obligations amount 112,389,000               112,389,000      
Customer Deposit [Member]                        
Contract With Customer Assets And Liabilities [Line Items]                        
Contract liabilities 3,660,000               3,660,000     $ 6,382,000
Prepaid Expenses and Other Current Assets [Member]                        
Contract With Customer Assets And Liabilities [Line Items]                        
Capitalized costs, net of amortization $ 45,000       $ 133,000       45,000 133,000    
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