Note 4 - Stock-based Compensation - Summary of Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Balance (in shares)	0	0
Options granted (in shares)		0	0
Balance (in shares)		0	0
Share-based Payment Arrangement, Option [Member]
Balance (in shares)	0
Options outstanding, weighted average exercise price (in dollars per share)	$ 0
Options outstanding, aggregate intrinsic value	$ 692	$ 0
Options granted (in shares)	721
Granted, weighted average exercise price (in dollars per share)	$ 15.77
Options exercised (in shares)	0
Exercised, weighted average exercise price (in dollars per share)	$ 0
Options forfeited (in shares)	0
Forfeited, weighted average exercise price (in dollars per share)	$ 0
Balance (in shares)	721	0
Options outstanding, weighted average exercise price (in dollars per share)	$ 15.77	$ 0
Options outstanding, weighted average contractual ife (Year)	9 years 9 months 18 days
Options outstanding, aggregate intrinsic value	$ (692)	$ 0
Exercisable (in shares)	0
Exercisable, weighted average exercise price (in dollars per share)	$ 0
Exercisable, options outstanding, aggregate intrinsic valueo	$ 0