Note 6 - Share-based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

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

	Years ended December 31,
	201 7			201 6		201 5
Restricted share units
Pretax compensation expense	$	28,679		$	29,938	$	27,898
Tax benefit		(4,385	)		11,347		10,629
Restricted share units, net of tax	$	33,064		$	18,591	$	17,269
Performance share units
Pretax compensation expense	$	9,612		$	10,687	$	9,330
Tax benefit		(1,470	)		4,050		3,555
Performance share awards, net of tax	$	11,082		$	6,637	$	5,775

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, 201 4		1,940,998		$	51.74
Granted		390,143			74.86
Vested		(783,483	)		39.45
Forfeited		(30,908	)		54.89
Unvested at December 31, 201 5		1,516,750		$	63.96
Granted		540,746			75.03
Vested		(520,619	)		54.78
Forfeited		(34,221	)		69.14
Unvested at December 31, 201 6		1,502,656		$	71.16
Granted		158,319			90.06
Vested		(380,702	)		67.29
Forfeited		(37,745	)		75.13
Unvested at December 31, 201 7		1,242,528		$	74.71

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, 201 4		433,895		$	62.23
Granted		160,574			74.37
Vested		(103,796	)		58.28
Forfeited		-			-
Unvested at December 31, 201 5		490,673		$	67.04
Granted		142,114			74.71
Vested		(148,733	)		62.84
Forfeited		-			-
Unvested at December 31, 201 6		484,054		$	70.58
Granted		-			-
Vested		(155,867	)		68.27
Forfeited		-			-
Unvested at December 31, 201 7		328,187		$	71.68

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, 201 4		98		$	20.40		0.86	$	6.3
Exercised		(95	)		20.35		-		5.8
Forfeited		(1	)		24.27		-		-
Outstanding at December 31, 201 5		2		$	20.76		0.05	$	0.1
Exercised		(2	)		20.76		-		-
Forfeited		-			-		-		-
Outstanding at December 31, 201 6		-			-		-		-