Note 11 - Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2015

Notes Tables

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	2015			2014
Risk–free interest rate		0.71	%		0.52	%
Expected volatility		16.5	%		17.3	%
Expected life, in years (years)	2.2			2.2
Expected dividend yield		2.73	%		2.68	%

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

	Number of Shares			Weighted Average Exercise Price		Aggregate Intrinsic Value
Options outstanding at January 1, 2014		1,074,552		$	46.44		-
Options granted		57,716			53.10		-
Options exercised		(157,590	)		45.97		-
Options cancelled		(20,000	)		46.69		-
Options outstanding at December 31, 2014		954,678			46.92		-
Options granted		56,792			61.47		-
Options exercised		(176,184	)		46.68		-
Options outstanding at September 30, 2015		835,286		$	47.95	$	10,839,000
Options exercisable at September 30, 2015		187,263		$	51.36	$	1,802,000

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

Options Outstanding September 30, 2015	Exercise Prices			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life in Years
778,694	$44.80	-	$52.93		$46.97		0.8
56,592	$61.25	-	$62.34		61.47		3.7
835,286					$47.95		0.96

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

	Number of Shares		Weighted Average Grant Date Fair Value		Aggregate Intrinsic Value
Non–vested restricted shares at January 1, 2014		12,000	$	34.46		-
Award shares granted		-		-		-
Award shares vested		6,000		34.46		-
Non–vested restricted shares at December 31, 2014		6,000		34.46		-
Award shares granted		-		-		-
Award shares vested		6,000		34.46		-
Non–vested restricted shares at September 30, 2015		-		-		-