Note 8 - Fair Value Measurements - Carrying Amount of Assets and Liabilities (Details) - Fair Value, Recurring [Member] - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Balance	$ 8,247,679	$ 2,537,317
Derivative Warrant Liability [Member]
Liability	8,247,679	2,537,317
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	8,247,679	2,537,317
Fair Value, Inputs, Level 3 [Member] | Derivative Warrant Liability [Member]
Liability	$ 8,247,679	$ 2,537,317