Note 2 - Significant Accounting Policies (Details Textual)	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Mar. 31, 2020
Contract with Customer, Liability, Revenue Recognized	$ 0	$ 6,000	$ 251,000	$ 517,000
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Number of Major Customers	2	2	2
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Customer Number 1 [Member]
Concentration Risk, Percentage	24.00%	40.00%	19.00%	36.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Customer Number 2 [Member]
Concentration Risk, Percentage	21.00%	17.00%	16.00%	17.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Number of Major Customers			3		2
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Customer Number 2 [Member]
Concentration Risk, Percentage					80.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Customer Number 3 [Member]
Concentration Risk, Percentage			70.00%