Note 6 - Stockholders' Equity and Stock-based Compensation - Stock-based Compensation Expense by Type (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Total stock-based compensation expense	$ 7,181	$ 5,191
Time-based Options [Member]
Total stock-based compensation expense	3,827	4,467
Performance-based Options [Member]
Total stock-based compensation expense	1,977	233
Market-based Options [Member]
Total stock-based compensation expense	1,130	0
Employee Stock Purchase Plan Award [Member]
Total stock-based compensation expense	$ 247	$ 491