Note 13 - Stock Option Plan (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Option Activity

	Number of options			Weighted average exercise price		Weighted average remaining contractual term (in years)		Aggregate intrinsic value
Outstanding at December 31, 2014		88,375		$	23.27
Exercised		(13,750	)		18.11
Forfeited		(12,750	)		31.80
Granted		21,000			29.25
Outstanding at December 31, 2015		82,875			24.33
Exercised		(22,700	)		20.90
Forfeited		(9,725	)		25.60
Granted		23,500			30.40
Outstanding at December 31, 2016		73,950			27.14
Exercised		(13,125	)		22.42
Forfeited		(300	)		22.58
Granted		25,000			37.60
Outstanding at December 31, 2017		85,525		$	30.94		2.66	$	1,151
Exercisable at December 31, 2017		19,175		$	24.48		0.72	$	382

Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding and Exercisable

	Options outstanding		Exercise price		Remaining life (in years)		Options exercisable		Exercise price
		6,650		23.20		0.06		6,650	$	23.20
		12,525		25.16		1.08		12,525		25.16
		17,850		29.25		2.08		—		—
		23,500		30.40		3.13		—		—
		25,000		37.60		4.13		—		—
Outstanding at December 31, 2017		85,525	$	30.94		2.66		19,175	$	24.48

Schedule of Intrinsic Value Related to Exercised Stock Options

	2017		2016		2015
Intrinsic value of stock options exercised	$	204	$	234	$	148