Note 3 - Stock-based Compensation and Shareholders' Equity (Tables)

9 Months Ended

Sep. 30, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Assumptions Used in Option Pricing Model

Nine months ended September 30,	2016			2015
Risk free interest rate		1.14	%		1.06	%
Dividend yield		3.78	%		3.86	%
Volatility		22.62	%		26.74	%
Expected life (years)		4.20			5.00

Stock Option Activity

	Number of options			Weighted average exercise price		Weighted average remaining contractual term (in years)		Aggregate intrinsic value
Outstanding at December 31, 2015		82,875		$	24.33
Granted		23,500			30.40
Exercised		(18,425	)		20.70
Forfeited		(9,725	)		25.61
Outstanding at September 30, 2016		78,225		$	26.85		2.74	$	560
Exercisable at September 30, 2016		23,100		$	22.38		0.87	$	268

	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
Granted		21,000			29.25
Exercised		(12,150	)		17.81
Forfeited		(12,650	)		31.87
Outstanding at September 30, 2015		84,575		$	24.25		2.50	$	444
Exercisable at September 30, 2015		30,375		$	20.87		0.89	$	262