Note 7 - Net Income (Loss) Per Share - Calculations of Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Basic:
Net income (loss)	$ 483	$ (6,709)	$ (320)	$ 17,625	$ (6,226)	$ 17,305
Basic (in shares)	16,356		20,856		16,468	20,879
Basic (in dollars per share)	$ 0.03		$ (0.02)		$ (0.38)	$ 0.83
Diluted:
Net income (loss)	$ 483	$ (6,709)	$ (320)	$ 17,625	$ (6,226)	$ 17,305
Basic (in shares)	16,356		20,856		16,468	20,879
Unvested restricted stock and DSU's (in shares)	0		0		0	0
Employee stock options (in shares)	0		0		0	0
Diluted (in shares)	16,356		20,856		16,468	20,879
Diluted (in dollars per share)	$ 0.03		$ (0.02)		$ (0.38)	$ 0.83