Note 13 - Stock-based Compensation - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Options outstanding (in shares)	233,384	229,531	276,266
Options outstanding, weighted-average exercise price (in dollars per share)	$ 97.78	$ 86.46	$ 72.38
Granted (in shares)	118,434	57,901	60,065
Granted, weighted-average exercise price (in dollars per share)	$ 48.24	$ 128.14	$ 105.79
Exercised (in shares)	(3,114)	(28,991)	(68,958)
Exercised, weighted-average exercise price (in dollars per share)	$ 30.58	$ 58.78	$ 57.00
Cancelled (in shares)	(84,712)	(25,057)	(37,842)
Cancelled, weighted-average exercise price (in dollars per share)	$ 89.32	$ 109.31	$ 67.92
Options outstanding (in shares)	263,992	233,384	229,531
Options outstanding, weighted-average exercise price (in dollars per share)	$ 79.07	$ 97.78	$ 86.46
Options exercisable (in shares)	102,692
Options exercisable, weighted-average exercise price (in dollars per share)	$ 90.22