Note 5 - Stock-based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Options outstanding, shares (in shares)	51
Options outstanding, weighted average exercise price (in dollars per share)	$ 39.14
Options outstanding, weighted average grant date fair value (in dollars per share)	$ 21.72
Granted, shares (in shares)	0	1
Stock price (in dollars per share)	$ 0
Granted, weighted average grant date fair value (in dollars per share)	$ 0
Exercised, shares (in shares)	0
Exercised, weighted average exercise price (in dollars per share)	$ 0
Exercised, weighted average grant date fair value (in dollars per share)	$ 0
Forfeited or expired, shares (in shares)	0
Forfeited or expired, weighted average exercise price (in dollars per share)	$ 0
Forfeited or expired, weighted average grant date fair value (in dollars per share)	$ 0
Options outstanding, shares (in shares)	51
Options outstanding, weighted average exercise price (in dollars per share)	$ 39.14
Options outstanding, weighted average grant date fair value (in dollars per share)	$ 21.72
Options outstanding, aggregate intrinsic value	$ 0
Options exercisable, shares (in shares)	51
Options exercisable, weighted average exercise price (in dollars per share)	$ 39.14
Options unvested, shares (in shares)	0