Note 11 - Stock-based Compensation - Stock Options Outstanding (Details) shares in Thousands	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Outstanding, exercise prices range lower limit (in dollars per share)	$ 1.85
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share)	$ 6.00
Number outstanding (in shares) | shares	153
Weighted average remaining contractual lifeWeighted average remaining contractual life (Year)	3 years 7 months 13 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.41
Shares Exercisable (in shares) | shares	150
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.49
Exercise Price Range 1 [Member]
Outstanding, exercise prices range lower limit (in dollars per share)	1.85
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share)	$ 2.83
Number outstanding (in shares) | shares	13
Weighted average remaining contractual lifeWeighted average remaining contractual life (Year)	6 years 6 months
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 2.08
Shares Exercisable (in shares) | shares	10
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 2.15
Exercise Price Range 2 [Member]
Outstanding, exercise prices range lower limit (in dollars per share)	5.00
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share)	$ 5.85
Number outstanding (in shares) | shares	88
Weighted average remaining contractual lifeWeighted average remaining contractual life (Year)	5 years 1 month 9 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.55
Shares Exercisable (in shares) | shares	88
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.55
Exercise Price Range 3 [Member]
Outstanding, exercise prices range lower limit (in dollars per share)	6.00
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share)	$ 6.00
Number outstanding (in shares) | shares	52
Weighted average remaining contractual lifeWeighted average remaining contractual life (Year)	4 months 20 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.00
Shares Exercisable (in shares) | shares	52
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 6.00