Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary Information for Restricted Stock Awards and Incentive Compensation Awards

The following table summarizes information for restricted stock awards and incentive compensation awards as of December 31, 2016:

	Restricted Stock - Service Based					Restricted Stock - Performance Based					Incentive Compensation
	Number of Awards			Weighted- Average Grant-Date Fair Value		Number of Awards			Weighted- Average Grant-Date Fair Value		Number of Awards			Weighted- Average Grant-Date Fair Value
January 1, 2016		288,563		$	120.92		36,607		$	117.76		37,340		$	106.45
Awarded		73,550		$	128.48		75,421		$	124.41		18,570		$	124.41
Distributed		(51,849	)	$	104.82		—		$	—		(14,665	)	$	107.01
Forfeited		(2,947	)	$	129.59		(711	)	$	124.41		(696	)	$	108.28
December 31, 2016		307,317		$	125.36		111,317		$	122.22		40,549		$	114.44

Summary Information for Stock Options

The following table includes summary information for stock options as of December 31, 2016:

	Number of Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Life (years)
Outstanding at January 1, 2016		686,012		$	95.43
Exercised		(276,240	)	$	98.67
Terminated		(2,881	)	$	89.06
Outstanding at December 31, 2016		406,891		$	93.27		3.9
Exercisable at December 31, 2016		324,979		$	82.63		3.0

Schedule of Stock-Based Compensation Expense

The following table summarizes stock-based compensation expense for the years ended December 31, 2016, 2015 and 2014, unrecognized compensation cost for nonvested awards at December 31, 2016 and the weighted-average period over which unrecognized compensation cost will be recognized:

(add 000, except year data)	Stock Options		Restricted Stock		Incentive Compensation		Directors’ Awards		Total
Stock-based compensation expense recognized for years    ended December 31:
2016	$	1,646	$	17,747	$	442	$	646	$	20,481
2015	$	2,679	$	9,809	$	376	$	725		13,589
2014	$	2,020	$	6,189	$	257	$	527		8,993
Unrecognized compensation cost at December 31, 2016:	$	1,045	$	19,533	$	340	$	—	$	20,918
Weighted-average period over which unrecognized    compensation cost will be recognized:	1.6 years		2.1 years		1.5 years			—

Stock-Based Compensation Expense in Future for Outstanding Awards

The following presents expected stock-based compensation expense in future periods for outstanding awards as of December 31, 2016:

(add 000)
2017	$	11,492
2018		7,547
2019		1,879
Total	$	20,918