Note 2 - Summary of Significant Accounting Policies - Reconciliation of Net Income and Number of Shares Used in Computations of Basic and Diluted EPS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Net income	$ 27,086,000	$ 3,000,000
Shares (denominator):
Basic weighted average common shares outstanding (in shares)	13,449,987	13,142,872
Add: Dilutive effect of common stock options (in shares)	522,158	25,853
Diluted weighted average common shares outstanding (in shares)	13,972,145	13,168,725
Earnings per common share:
Basic earnings per common share (in dollars per share)	$ 2.01	$ 0.23
Diluted earnings per common share (in dollars per share)	$ 1.94	$ 0.23