Note 6 - Share-based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

Notes Tables

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Years ended December 31,
	2015		2014		2013
Restricted share units
Pretax compensation expense	$	27,898	$	27,256	$	25,606
Tax benefit		10,629		10,360		9,769
Restricted share units, net of tax	$	17,269	$	16,896	$	15,837
Performance share units
Pretax compensation expense	$	9,330	$	7,882	$	5,941
Tax benefit		3,555		2,996		2,266
Performance share awards, net of tax	$	5,775	$	4,886	$	3,675
Stock options
Pretax compensation expense	$	-	$	195	$	807
Tax benefit		-		74		308
Stock option expense, net of tax	$	-	$	121	$	499

Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]

Restricted Share Units	Number of Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2012		2,835,466		$	32.75
Granted		522,062			71.50
Vested		(865,147	)		31.92
Forfeited		(70,951	)		36.67
Unvested at December 31, 2013		2,421,430		$	41.49
Granted		447,780			75.61
Vested		(808,914	)		37.33
Forfeited		(119,298	)		47.81
Unvested at December 31, 2014		1,940,998		$	51.74
Granted		390,143			74.86
Vested		(783,483	)		39.45
Forfeited		(30,908	)		54.89
Unvested at December 31, 2015		1,516,750		$	63.96

Schedule of Nonvested Performance-based Units Activity [Table Text Block]

Performance Share Units	Number of Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2012		309,500		$	47.07
Granted		160,500			71.90
Vested		(61,975	)		47.48
Forfeited		-			-
Unvested at December 31, 2013		408,025		$	56.78
Granted		106,945			76.22
Vested		(81,075	)		53.26
Forfeited		-			-
Unvested at December 31, 2014		433,895		$	62.23
Granted		160,574			74.37
Vested		(103,796	)		58.28
Forfeited		-			-
Unvested at December 31, 2015		490,673		$	67.04

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

Stock Options	Number of Shares (in thousands)			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in millions)
Outstanding at December 31, 2012		1,031		$	16.63		2.35	$	44.4
Exercised		(585	)		14.77		-		34.0
Forfeited		(6	)		19.89		-		-
Outstanding at December 31, 2013		440		$	19.08		1.67	$	25.6
Exercised		(341	)		18.70		-		19.9
Forfeited		(1	)		19.08		-		-
Outstanding at December 31, 2014		98		$	20.40		0.86	$	6.3
Exercised		(95	)		20.35		-		5.8
Forfeited		(1	)		24.27		-		-
Outstanding at December 31, 2015		2		$	20.76		0.05	$	0.1
Exercisable		2		$	20.76		0.05	$	0.1