Note 2 - Summary of Significant Accounting Policies - Securities Potentially Dilute Calculation of Diluted Earnings Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Antidilutive securities (in shares)	1,157,914	1,552,820
Warrants to Purchase Common Stock - Liability Classified [Member]
Antidilutive securities (in shares)	54,989	55,963
Warrants to Purchase Common Stock - Equity Classified [Member]
Antidilutive securities (in shares)		6
Convertible 2017 Notes [Member]
Antidilutive securities (in shares)	974,139	1,071,674
Share-based Payment Arrangement, Option [Member]
Antidilutive securities (in shares)	1,561	2,311
Stock Appreciation Rights (SARs) [Member]
Antidilutive securities (in shares)	127,225	132,566
Restricted Stock [Member]
Antidilutive securities (in shares)		290,300