Note 17 - Business Segments - Total Business Segments Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Mar. 31, 2020
Total assets	$ 192,167	$ 168,866	$ 168,866
Operating Segments [Member] | Grid [Member]
Total assets	121,355		81,253
Operating Segments [Member] | Wind [Member]
Total assets	6,949		6,098
Corporate, Non-Segment [Member]
Total assets	$ 63,863		$ 81,515