Note 13 - Stock Option Plans (Tables)

12 Months Ended

Dec. 31, 2016

Notes Tables

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

	2016				2015
Options outstanding at January 1			274,500				274,500
Options cancelled			0				(8,000	)
Options exercised			(12,000	)			(4,000	)
Options granted			42,000				12,000
Options outstanding at December 31			304,500				274,500
Options available for grant at December 31			834,000				876,000
Options exercisable at December 31			256,500				254,500
Exercise price ranges per share:
Granted	$3.50	-	$3.89			$2.97
Exercised	$0.69	-	$1.66			$2.08
Outstanding	$0.69	-	$3.89		$0.69	-	$3.84
Weighted average exercise price per share:
Granted	$		3.78		$		2.97
Exercised	$		1.18		$		2.08
Outstanding at December 31	$		2.06		$		1.76
Exercisable at December 31	$		1.76		$		1.72

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

Options Outstanding:
Range of  Exercise Price			Number Outstanding		Wgt. Avg. Contractual Life Remaining (in years)	Wgt. Avg. Exercise Price		Aggregate Intrinsic Value
$0.69	-	$1.72		226,500	4.8	$	1.54	$	593,970
$2.97	-	$3.89		78,000	6.8	$	3.59	$	68,880
$0.69	-	$3.89		304,500	5.3	$	2.06	$	662,850

Exercisable [Member]

Notes Tables

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

Options Exercisable:
Range of  Exercise Price			Number Exercisable		Wgt. Avg. Contractual Life Remaining (in years)	Wgt. Avg. Exercise Price		Aggregate Intrinsic Value
$0.69	-	$1.72		226,500	4.8	$	1.54	$	566,970
$2.97	-	$3.84		30,000	2.4	$	3.45	$	68,880
$0.69	-	$3,84		256,500	4.5	$	1.76	$	635,850