Note 10 - Stock Compensation Plans - Vesting of Non-vested RSU Grants (Details) - Restricted Stock Units (RSUs) [Member]	Dec. 31, 2020 shares
RSUs vesting (in shares)	324,250
Vesting in 2021 [Member]
RSUs vesting (in shares)	305,250
Vesting in 2022 [Member]
RSUs vesting (in shares)	9,000
Vesting in 2023 [Member]
RSUs vesting (in shares)	10,000