Note 10 - Stockholders' Equity - Non-vested Stock Options Activity (Details) - $ / shares			12 Months Ended
	Apr. 07, 2019	Dec. 14, 2018	Dec. 31, 2019	Dec. 31, 2018
Outstanding at January 1, 2019 (in shares)			302,368
Granted (in shares)	800,000	214,000	11,450
Granted (in dollars per share)			$ 3.30	$ 3.20
Vested (in shares)			(300,000)
Cancelled/forfeited (in shares)			(22,011)
Cancelled/forfeited (in dollars per share)			$ 9.42
Outstanding, options (in shares)			291,807	302,368
Non-vested Stock Options [Member]
Outstanding at January 1, 2019 (in shares)			212,172
Outstanding at January 1, 2019 (in dollars per share)			$ 6.39
Granted (in shares)			11,450
Granted (in dollars per share)			$ 3.30
Vested (in shares)			(63,675)
Vested (in dollars per share)			$ 6.73
Cancelled/forfeited (in shares)			(15,264)
Cancelled/forfeited (in dollars per share)			$ 2.74
Outstanding, options (in shares)			144,683	212,172
Outstanding at December 31, 2019 (in dollars per share)			$ 6.38	$ 6.39