Note 7 - Share-based Compensation - Stock-settled Stock Appreciation Rights Transactions (Details) - Stock Appreciation Rights (SARs) [Member] - USD ($) $ / shares in Units, $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2021	Dec. 31, 2020	Jan. 01, 2021
Outstanding SARS (in shares)		317,128
Outstanding (in dollars per share)		$ 13.47
Outstanding SARS, weighted average remaining life (Year)		2 years 10 months 17 days	3 years 4 months 9 days
Outstanding SARS, aggregate intrinsic value		$ 2,899		$ 2,031
Granted SARs (in shares)	[1]	31,687
Granted SARS, weighted average exercise price (in dollars per share)	[1]	$ 25.75
Exercised SARs (in shares)		(26,438)
Exercised SARS, weighted average exercise price (in dollars per share)		$ 14.74
Outstanding SARS (in shares)		322,377	317,128
Outstanding SARS, weighted average exercise price (in dollars per share)		$ 14.57	$ 13.47
Exercisable (in shares)		160,586
Exercisable, weighted average exercise price (in dollars per share)		$ 15.29
Exercisable, weighted average remaining life (Year)		2 years 2 months 12 days
Exercisable, aggregate intrinsic value		$ 1,296

[1] The weighted average grant date fair value of SARs granted was $10.09 per share.