Note 11 - Stockholders' Equity - Stock by Class (Details) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Common stock shares authorized (in shares)	125,000,000	125,000,000
Common stock par value (in dollars per share)	$ 0.001	$ 0.001
Common stock shares issued (in shares)	52,259,303	50,554,179
Preferred stock shares authorized (in shares)	3,000,000	3,000,000
Preferred stock par value (in dollars per share)	$ 0	$ 0
Preferred stock shares issued (in shares)	0	0