Note 13 - Stock-based Compensation - Common Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock Options Outstanding, number of shares (in shares)	821,470	826,498	835,786
Common Stock Options Outstanding, weighted-average exercise price per share (in dollars per share)	$ 11.00	$ 11.00	$ 11.00
Common Stock Options Granted, number of shares (in shares)	249,283	0	0
Common Stock Options Granted, weighted-average exercise price per share (in dollars per share)	$ 5.76	$ 0	$ 0
Common Stock Options Exercised, number of shares (in shares)	0	0	(9,288)
Common Stock Options Exercised, weighted-average exercise price per share (in dollars per share)	$ 0	$ 0	$ 11.00
Common Stock Options Forfeited, number of shares (in shares)	(2,736)	(5,028)	0
Common Stock Options Forfeited, weighted-average exercise price per share (in dollars per share)	$ 11.00	$ 11.00	$ 0
Common Stock Options Outstanding, number of shares (in shares)	1,068,017	821,470	826,498
Common Stock Options Outstanding, weighted-average exercise price per share (in dollars per share)	$ 9.78	$ 11.00	$ 11.00
Common Stock Options Exercisable, number of shares (in shares)	818,734	821,470	826,498
Common Stock Options Exercisable, weighted-average exercise price per share (in dollars per share)	$ 11.00	$ 11.00	$ 11.00