Note 5 - Short-term Investments - Marketable Securities (Details) $ in Thousands, $ in Thousands	Sep. 30, 2021 USD ($)	Sep. 30, 2021 CAD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2021 CAD ($)
Term deposits issued in US currency earning interest at ranges between 0.19% and 0.30% and maturing on various dates from November 4, 2021, to December 20, 2021	$ 13,861		$ 9,789
Deposits [Member]
Term deposits issued in US currency earning interest at ranges between 0.19% and 0.30% and maturing on various dates from November 4, 2021, to December 20, 2021	$ 12,419		$ 7,542
Canadian Deposits [Member]
Term deposits issued in US currency earning interest at ranges between 0.19% and 0.30% and maturing on various dates from November 4, 2021, to December 20, 2021		$ 1,442		$ 2,247