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Note 3 - Accounts Receivable (Details Textual)
$ in Thousands
3 Months Ended 6 Months Ended 12 Months Ended
Jul. 31, 2019
USD ($)
Jul. 31, 2018
Jul. 31, 2019
USD ($)
Jul. 31, 2018
Jan. 31, 2019
USD ($)
Accounts Receivable, Outstanding for Several Years $ 4,400   $ 4,400   $ 4,700
Contract Receivable Retainage, Total 3,700   3,700   3,700
Proceeds from Collection of Accounts Receivable Outstanding for Several Years     300   $ 700
Allowance for Doubtful Accounts Receivable Outstanding for Several Years $ 0   $ 0    
Revenue Benchmark [Member] | Customer Concentration Risk [Member]          
Number of Major Customers 0 1 0 2  
Concentration Risk, Percentage   13.00%   23.00%  
Accounts Receivable [Member] | Customer Concentration Risk [Member]          
Number of Major Customers     3   3
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Three Customers [Member]          
Concentration Risk, Percentage     29.30%   39.40%
Other Noncurrent Assets [Member]          
Contract Receivable Retainage, Total $ 3,500   $ 3,500   $ 3,500