Share-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

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

The following table presents stock options outstanding during 2016, 2015 and 2014 under these plans (in thousands, except for per share data):

	Number		Weighted- Average Exercise Price		Aggregate Intrinsic Value
Options outstanding at December 31, 2013	1,135,105		$	49.09	$	19,564
Options awarded	—		—
Options exercised	(323,004	)	49.17
Options forfeited	(15,509	)	45.71
Options expired	(2,701	)	47.98
Options outstanding at December 31, 2014	793,891		49.05		8,725
Options awarded	—		—
Options exercised	(286,678	)	47.86
Options forfeited	(22,304	)	48.90
Options expired	(4,874	)	51.32
Options outstanding at December 31, 2015	480,035		49.75		4,821
Options awarded	—		—
Options exercised	(249,404	)	47.60
Options forfeited	(4,098	)	55.44
Options expired	(8,009	)	53.43
Options outstanding at December 31, 2016	218,524		$	51.95	$	6,793
Options vested at:
December 31, 2014	347,633		$	48.85	$	3,889
December 31, 2015	243,395		48.17		2,829
December 31, 2016	93,117		46.22		3,429

Schedule of Share-based Compensation, Outstanding and Vested Stock Options [Table Text Block]

The following table summarizes information concerning currently outstanding and vested stock options:

	Options Outstanding			Options Vested
		Weighted				Weighted
		Average	Weighted		Weighted	Average
		Remaining	Average		Average	Remaining
Exercise	Number	Contractual	Exercise	Number	Exercise	Contractual
Prices	Outstanding	Life (years)	Price	Vested	Price	Life (years)
$36.65	36,722	1.45	$36.65	36,722	$36.65	1.45
48.30	14,208	2.32	48.30	6,906	48.30	1.57
48.46	21,138	0.81	48.46	21,138	48.46	0.81
54.33	3,628	0.03	54.33	3,628	54.33	0.03
55.74	51,570	4.28	55.74	5,008	55.74	2.03
55.94	48,800	3.08	55.94	12,260	55.94	1.72
58.76	42,458	3.62	58.76	7,455	58.76	1.70

Schedule of Nonvested Share Activity [Table Text Block]

The following represents a summary of the non-vested stock awards as of December 31, 2016 (in thousands):

	Shares		Weighted Average Grant Date Fair Value
Non-vested at January 1, 2014	647,989
Granted	206,621		$64.96
Vested	(140,820	)	$44.56
Forfeited	(25,179	)	$56.26
Non-vested at December 31, 2014	688,611
Granted	312,755		$57.66
Vested	(114,045	)	$50.15
Forfeited	(96,212	)	$58.33
Non-vested at December 31, 2015	791,109
Granted	256,670		$55.35
Vested	(213,941	)	$55.87
Forfeited	(47,132	)	$57.86
Non-vested at December 31, 2016	786,706