Note 5 - Income Taxes - Deferred Income Taxes (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
Deferred tax assets:
Accrued expenses	$ 298	$ 346
Deferred stock compensation	412	353
Bad debt and inventory reserves	22	22
Total deferred tax assets	732	721
Deferred tax liabilities:
Property and equipment	1,853	1,717
Total net deferred taxes	$ (1,121)	$ (996)