Note 16 - Subsequent Events (Details Textual) - USD ($) $ / shares in Units, $ in Millions	Mar. 22, 2021	Mar. 17, 2021	Dec. 31, 2020	Dec. 31, 2019
Preferred Stock, Par or Stated Value Per Share (in dollars per share)			$ 0.0001	$ 0.0001
Subsequent Event [Member] | Series C Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.0001
Subsequent Event [Member] | Series C Preferred Stock [Member] | Purchasers [Member]
Proceeds from Issuance of Preferred Stock, Preference Stock, and Warrants, Total	$ 24.5