Note 8 - Fair Value Measurements - Carrying Amount of Assets and Liabilities (Details) - Fair Value, Recurring [Member] - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Balance	$ 9,691,271	$ 8,247,679
Derivative Warrant Liability [Member]
Liability	9,691,271	8,247,679
Fair Value, Inputs, Level 1 [Member]
Balance
Fair Value, Inputs, Level 1 [Member] | Derivative Warrant Liability [Member]
Liability
Fair Value, Inputs, Level 2 [Member]
Balance
Fair Value, Inputs, Level 2 [Member] | Derivative Warrant Liability [Member]
Liability
Fair Value, Inputs, Level 3 [Member]
Balance	9,691,271	8,247,679
Fair Value, Inputs, Level 3 [Member] | Derivative Warrant Liability [Member]
Liability	$ 9,691,271	$ 8,247,679