Note 5 - Income Taxes - Deferred Income Taxes (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Deferred tax assets:
Accrued expenses	$ 287	$ 298
Deferred stock compensation	469	412
Bad debt and inventory reserves	24	22
Total deferred tax assets	780	732
Deferred tax liabilities:
Property and equipment	(1,750)	(1,853)
Total net deferred tax liabilities	$ (970)	$ (1,121)