Note 9 - Stock Compensation Plans - Vesting of Non-vested RSU Grants (Details) - Restricted Stock Units (RSUs) [Member]	Mar. 31, 2021 shares
RSUs vesting (in shares)	311,750
Vesting in 2021 [Member]
RSUs vesting (in shares)	301,750
Vesting in 2022 [Member]
RSUs vesting (in shares)	0
Vesting in 2023 [Member]
RSUs vesting (in shares)	10,000