Note 5 - Fair Value of Financial Instruments - Fair Value of Available-for-sale Securities (Details) - USD ($)
Dec. 31, 2021
Mar. 31, 2021
Total $ 57,293,870 $ 64,860,822
Less than 1 year 30,114,318  
1-3 years 22,148,686  
3-5 years $ 5,030,866