Note 10 - Shareholders' Equity and Stock-based Compensation - Stock Options Roll Forward (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($) $ / shares shares		Dec. 31, 2020 shares
Balance (in shares)	690
Balance, total (in shares)	907
Balance, weighted average exercise price (in dollars per share) | $ / shares	$ 6.51	[1]
Awards granted (in shares)	0
Awards granted, total (in shares)	130
Awards granted, weighted average exercise price (in dollars per share) | $ / shares	$ 0	[1]
Awards exercised or released (in shares)	(122)
Awards exercised or released, total (in shares)	(220)
Awards exercised or released (in dollars per share) | $ / shares	$ 5.73	[1]
Balance (in shares)	568
Balance, total (in shares)	817
Balance, weighted average exercise price (in dollars per share) | $ / shares	$ 6.68	[1]
Balance, intrinsic value | $	$ 11,048
Balance, Exercisable (in shares)	568
Exercisable, total (in shares)	568
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 6.68	[1]
Exercisable, intrinsic value | $	$ 6,520
Available for future grant at December 31, 2020 (in shares)	471		73
Restricted Stock Units (RSUs) [Member]
Balance, outstanding RSU (in shares)	217
RSU Awards granted (in shares)	130
RSU Awards exercised or released (in shares)	(98)
Balance, outstanding RSU (in shares)	249

[1] The weighted average exercise price calculation does not include outstanding RSUs