Note 8 - Basic and Diluted Earnings Per Common Share - Reconciliation of Net Income and Number of Shares Used in Computations of Basic and Diluted EPS (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 30, 2022	Mar. 31, 2021	Mar. 30, 2021
Net income	$ 1,522,000	$ 1,522,000	$ 3,719,000	$ 3,719,000
Shares (denominator):
Basic weighted average common shares outstanding (in shares)	13,058,871	13,058,871	13,342,398	13,342,398
Add: dilutive effect of common stock options (in shares)	100,619		375,006
Diluted weighted average common shares outstanding (in shares)	13,159,490	13,159,490	13,717,404	13,717,404
Earnings per common share:
Basic (in dollars per share)	$ 0.12	$ 0.12	$ 0.28	$ 0.28
Diluted (in dollars per share)	$ 0.12	$ 0.12	$ 0.27	$ 0.27