Note 14 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

Notes Tables

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

	Year Ended December 31,
	2015			2014			2013
Risk-free interest rate		0.71	%		0.52	%		0.25	%
Expected volatility		16.5	%		17.3	%		31.3	%
Expected life, in years		2.2			2.2			2.1
Expected dividend yield		2.73	%		2.68	%		2.81	%

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, 2013		1,134,602		$	46.75	$	-
Options granted		57,672			47.95		-
Options exercised		(19,722	)		45.63		-
Options cancelled		(98,000	)		51.11		-
Options outstanding at December 31, 2013		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		56,210			61.47		-
Options exercised		(389,498	)		47.06		-
Options cancelled		-			-		-
Options outstanding at December 31, 2015		621,390		$	48.15		8,422,000
Options exercisable at December 31, 2015		161,000		$	52.31	$	1,512,000

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

Options Outstanding December 31, 2015		Exercise Prices			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life in Years
	576,390	$44.80	-	$52.93		$47.12		0.6
	45,000		$61.25			$61.25		4.3
	621,390					$48.15		0.9

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
Unvested restricted shares at January 1, 2013		18,000	$	34.46	$	-
Award shares granted		-		-		-
Award shares vested		6,000		34.46		-
Unvested restricted shares at December 31, 2013		12,000		34.46		-
Award shares granted		-		-		-
Award shares vested		6,000		34.46		-
Unvested restricted shares at December 31, 2014		6,000		34.46
Award shares granted		-		-		-
Award shares vested		6,000		34.46		-
Unvested restricted shares at December 31, 2015		-	$	-	$	-