Note 9 - 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		9 Months Ended
	Jul. 01, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income	$ 1,103,000	$ 1,539,000	$ 1,103,000	$ 3,007,000	$ 2,457,000
Shares (denominator):
Basic weighted average common shares outstanding (in shares)	14,732,173	13,795,007	14,732,173	14,031,518	14,962,606
Add: dilutive effect of common stock options (in shares)		58,612	201,253	44,515	113,334
Diluted weighted average common shares outstanding (in shares)	14,933,426	13,853,619	14,933,426	14,076,033	15,075,940
Earnings per common share:
Basic (in dollars per share)	$ 0.07	$ 0.11	$ 0.07	$ 0.21	$ 0.16
Diluted (in dollars per share)	$ 0.07	$ 0.11	$ 0.07	$ 0.21	$ 0.16