Note 2 - Significant Accounting Policies (Details Textual) - USD ($) shares in Thousands, $ / shares in Thousands	3 Months Ended		6 Months Ended		15 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Mar. 31, 2022
Cash, Uninsured Amount	$ 687,000		$ 687,000		$ 687,000	$ 887,000
Contract with Customer, Liability, Revenue Recognized			62,000		$ 27,000
Advertising Expense	$ 8,796	$ 7,785	$ 15,031	$ 14,788
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)			0	0
Earnings Per Share, Basic (in dollars per share)	$ 0	$ (0)	$ 0	$ (0)
Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)			5 years
Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)			7 years
Electronic Products [Member]
Warranty Term (Year)			90 years