Note 11 - Stockholders' Equity - Non-vested Stock Options Activity (Details) - $ / shares		12 Months Ended
	Jun. 04, 2020	Dec. 31, 2020	Dec. 31, 2019
Outstanding, options (in shares)		291,807
Granted (in shares)	565,500	615,500
Granted, Weighted-Average Grant Date Fair Value (in dollars per share)		$ 5.05	$ 3.30
Cancelled/forfeited (in shares)		(17,671)
Cancelled/forfeited, Weighted-Average Grant Date Fair Value (in dollars per share)		$ 5.63
Outstanding, options (in shares)		889,636	291,807
Non-vested Stock Options [Member]
Outstanding, options (in shares)		144,683
Outstanding, Weighted-Average Grant Date Fair Value (in dollars per share)		$ 6.38
Granted (in shares)		615,500
Granted, Weighted-Average Grant Date Fair Value (in dollars per share)		$ 5.05
Vested (in shares)		(88,683)
Vested, Weighted-Average Grant Date Fair Value (in dollars per share)		$ 5.72
Cancelled/forfeited (in shares)		(12,700)
Cancelled/forfeited, Weighted-Average Grant Date Fair Value (in dollars per share)		$ 4.82
Outstanding, options (in shares)		658,800	144,683
Outstanding, Weighted-Average Grant Date Fair Value (in dollars per share)		$ 5.25	$ 6.38