Note 5 - Income Taxes - Deferred Income Taxes (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Deferred tax assets:
Accrued expenses	$ 346	$ 474
Deferred stock compensation	353	334
Bad debt and inventory reserves	22	29
Total deferred tax assets	721	837
Deferred tax liabilities:
Property and equipment	1,717	1,925
Total net deferred taxes	$ (996)	$ (1,088)