Note 2 - Earnings Per Share - Securities Potentially Dilute Calculation of Diluted Earnings Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive securities (in shares)	220,099	6,837,786
Warrants to Purchase Common Stock - Liability Classified [Member]
Antidilutive securities (in shares)	56,735	54,669
Warrants to Purchase Common Stock - Equity Classified [Member]
Antidilutive securities (in shares)	94,108
Convertible 2020/21 Notes [Member]
Antidilutive securities (in shares)		6,713,817
Share-based Payment Arrangement, Option [Member]
Antidilutive securities (in shares)	1,517	1,561
Stock Appreciation Rights (SARs) [Member]
Antidilutive securities (in shares)	67,739	67,739