Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary Information for Restricted Stock Awards and Incentive Compensation Stock Awards

The following table summarizes information for restricted stock awards and incentive compensation stock awards for 2018:

	Restricted Stock - Service Based					Restricted Stock - Performance Based					Incentive Compensation Stock
	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, 2018		314,840		$	151.84		139,999		$	150.34		38,510		$	166.67
Awarded		64,352		$	211.03		37,138		$	212.12		18,180		$	212.12
Distributed		(88,674	)	$	159.04		(20,219	)	$	126.01		(20,992	)	$	138.54
Forfeited		(12,371	)	$	211.63		(4,979	)	$	182.90		(322	)	$	184.74
December 31, 2018		278,147		$	158.29		151,939		$	174.74		35,376		$	206.55

Summary Information for Stock Options

The following table includes summary information for stock options as of December 31, 2018:

	Number of Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Life (years)
Outstanding at January 1, 2018		301,958		$	91.44
Exercised		(89,557	)	$	81.06
Terminated		(2,011	)	$	83.32
Outstanding at December 31, 2018		210,390		$	95.93		3.6
Exercisable at December 31, 2018		197,241		$	92.02		3.4

Schedule of Stock-Based Compensation Expense

The following table summarizes stock-based compensation expense for the years ended December 31, 2018, 2017 and 2016, unrecognized compensation cost for nonvested awards at December 31, 2018 and the weighted-average period over which unrecognized compensation cost will be recognized:

(add 000, except year data)	Stock Options		Restricted Stock		Incentive Compensation Stock		Directors’ Awards		Total
Stock-based compensation expense recognized for years    ended December 31:
2018	$	242	$	27,650	$	729	$	632	$	29,253
2017	$	684	$	28,657	$	661	$	458	$	30,460
2016	$	1,646	$	17,747	$	442	$	646	$	20,481
Unrecognized compensation cost at December 31, 2018:	$	50	$	21,992	$	495	$	—	$	22,537
Weighted-average period over which unrecognized    compensation cost will be recognized:	0.4 years		1.6 years		1.6 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, 2018:

(add 000)
2019	$	16,191
2020		5,843
2021		409
2022		94
Total	$	22,537