Note 15 - Stockholders Equity - Stock Options Outstanding and Exercisable (Details)	12 Months Ended
	Dec. 31, 2021 $ / shares shares
Options outstanding, number (in shares) | shares	5,977,179
Options outstanding, weighted average remaining contractual term (Year)	7 years 2 months 12 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 3.72
Options exercisable (in shares) | shares	2,907,668
Options exercisable, weighted average remaining contractual term (Year)	5 years 3 months 7 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 4.52
Range One [Member]
Exercise price range, lower limit (in dollars per share)	1.35
Exercise price range, upper limit (in dollars per share)	$ 3.64
Options outstanding, number (in shares) | shares	4,675,428
Options outstanding, weighted average remaining contractual term (Year)	7 years 5 months 15 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 2.67
Options exercisable (in shares) | shares	1,896,935
Options exercisable, weighted average remaining contractual term (Year)	4 years 11 months 15 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 2.92
Range Two [Member]
Exercise price range, lower limit (in dollars per share)	4.26
Exercise price range, upper limit (in dollars per share)	$ 7.95
Options outstanding, number (in shares) | shares	1,250,316
Options outstanding, weighted average remaining contractual term (Year)	6 years 3 months 25 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 6.82
Options exercisable (in shares) | shares	965,929
Options exercisable, weighted average remaining contractual term (Year)	5 years 10 months 17 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 6.69
Range Three [Member]
Exercise price range, lower limit (in dollars per share)	12.45
Exercise price range, upper limit (in dollars per share)	$ 26.10
Options outstanding, number (in shares) | shares	31,156
Options outstanding, weighted average remaining contractual term (Year)	6 years 9 months
Options outstanding, weighted average exercise price (in dollars per share)	$ 18.02
Options exercisable (in shares) | shares	24,558
Options exercisable, weighted average remaining contractual term (Year)	6 years 8 months 15 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 18.19
Range Four [Member]
Exercise price range, lower limit (in dollars per share)	27.00
Exercise price range, upper limit (in dollars per share)	$ 33.00
Options outstanding, number (in shares) | shares	11,900
Options outstanding, weighted average remaining contractual term (Year)	3 years
Options outstanding, weighted average exercise price (in dollars per share)	$ 27.62
Options exercisable (in shares) | shares	11,882
Options exercisable, weighted average remaining contractual term (Year)	2 years 11 months 26 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 27.62
Range Five [Member]
Exercise price range, lower limit (in dollars per share)	36.00
Exercise price range, upper limit (in dollars per share)	$ 94.65
Options outstanding, number (in shares) | shares	8,379
Options outstanding, weighted average remaining contractual term (Year)	5 years 8 months 8 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 45.42
Options exercisable (in shares) | shares	8,364
Options exercisable, weighted average remaining contractual term (Year)	5 years 8 months 8 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 45.39