Note 7 - Stock-based Awards - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Outstanding (in shares)		604
Outstanding, weighted average exercise price (in dollars per share)		$ 14.31
Outstanding, weighted average remaining contractual life (Year)		6 years 1 month 6 days	7 years
Exercised (in shares)		(1)
Exercised, weighted average exercise price (in dollars per share)		$ 4.07
Forfeited (in shares)		(29)
Forfeited, weighted average exercise price (in dollars per share)		$ 3.47
Outstanding (in shares)		574	604
Outstanding, weighted average exercise price (in dollars per share)		$ 14.23	$ 14.31
Outstanding, aggregate intrinsic value	[1]	$ 0.1
Exercisable (in shares)		464
Exercisable, weighted average exercise price (in dollars per share)		$ 15.12
Exercisable, weighted average remaining contractual life (Year)		5 years 8 months 12 days

[1] The aggregate intrinsic value on this table was calculated based on the amount, if any, by which the closing market price of the Company’s stock on December 31 of the applicable year exceeded the exercise price of any of the underlying options, multiplied by the number of shares subject to each such option. The closing stock price as of December 31, 2021, and 2020 was $7.02 and $5.09, respectively.