Note 6 - Shareholders' Equity - Summary of Certain Additional Information about Stock Options (Details) - Share-Based Payment Arrangement, Option [Member] - USD ($)	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Weighted average grant-date fair value of options granted during the period (in dollars per share)	$ 0	$ 1.84
Options in-the-money (in shares) (in shares)	203,316	312,661
Aggregate intrinsic value of options exercised during the period	$ 3,616	$ 1.20

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration