Note 9 - 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																12 Months Ended
	Dec. 31, 2021	[1]	Sep. 30, 2021	[1]	Jun. 30, 2021		Mar. 31, 2021		Dec. 31, 2020	[1]	Sep. 30, 2020	[1]	Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2021	Dec. 31, 2020
Basic:
Net income (loss)	$ (8,634)		$ 18,333		$ (320)		$ 17,625		$ (7,353)		$ (4,343)		$ (9,911)		$ (16,008)		$ 27,004	$ (37,615)
Basic (in shares)																	19,827	20,751
Basic (in dollars per share)	$ (0.51)	[2]	$ 0.88	[2]	$ (0.02)	[2]	$ 0.84	[2]	$ (0.35)	[2]	$ (0.21)	[2]	$ (0.48)	[2]	$ (0.77)	[2]	$ 1.36	$ (1.81)
Diluted:
Net income (loss)	$ (8,634)		$ 18,333		$ (320)		$ 17,625		$ (7,353)		$ (4,343)		$ (9,911)		$ (16,008)		$ 27,004	$ (37,615)
Diluted (in shares)																	19,827	20,751
Diluted (in dollars per share)	$ (0.51)	[2]	$ 0.88	[2]	$ (0.02)	[2]	$ 0.84	[2]	$ (0.35)	[2]	$ (0.21)	[2]	$ (0.48)	[2]	$ (0.77)	[2]	$ 1.36	$ (1.81)

[1] The three months ended December 31, 2019 includes equity income of $1.4 million related to an equity method investment that should have been recorded during the three months ended September 30, 2019. There was no impact on the full year results.

[2] Per share amounts for the quarters have each been calculated separately. Accordingly, quarterly amounts may not add to the annual amounts because of differences in the average common shares outstanding during each period. Additionally, in regard to diluted per share amounts only, quarterly amounts may not add to the annual amounts because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive, and because of the adjustments to net income (loss) for the dilutive effect of common stock equivalents and convertible securities at our ownership interests.