Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Share-Based Compensation [Abstract]

Share-Based Compensation Options Outstanding Rollforward

	2019				2018				2017
				Weighted				Weighted				Weighted
				Average				Average				Average
		Number		Exercise		Number		Exercise		Number		Exercise
		of		Price		of		Price		of		Price
		Options		per Share		Options		per Share		Options		per Share
Options outstanding January 1,		2,420,922	$	201.31		2,408,917	$	192.12		1,995,440	$	150.83
Granted		120,000		221.12		200,000		194.29		1,096,000		223.58
Exercised		(191,255)		174.55		(179,995)		69.53		(482,523)		88.07
Cancelled		(10,000)		197.90		(8,000)		223.50		(200,000)		203.64
Options outstanding December 31,		2,339,667	$	204.53		2,420,922	$	201.31		2,408,917	$	192.12
Options exercisable at December 31,		1,501,667	$	196.37		1,147,122	$	178.31		848,250	$	143.55

Share-Based Compensation Valuation Assumptions

	2019		2018		2017
Stock option expense for the year (in 000's) (a)	$	4,950	$	17,162	$	8,707
Aggregate exercise date intrinsic value of options exercised during the year (in 000's)	$	11,848	$	25,117	$	61,334
Average assumptions used in valuing options with the Black-Scholes method:
Expected life of options in years, based upon historical experience		5		5		5
Risk-free interest rate		2.3%		2.7%		1.9%
Expected volatility, based upon historical volatility		8.9%		12.5%		17.9%
Expected dividend yield		3.6%		4.1%		3.6%
Average estimated value of options granted during the year	$	9.61	$	13.09	$	23.49

(a) Amounts for 2018 include $8.1 million, in connection with the acceleration of amortization on grants discussed above. Amounts for 2017 reflect a reduction in compensation expense of $0.8 million related to stock options forfeited during the period.

Share-Based Compensation Restricted Units Outstanding And Vesting

	2019				2018				2017
		Number of		Grant Date		Number of		Grant Date		Number of		Grant Date
		Restricted		Aggregate		Restricted		Aggregate		Restricted		Aggregate
		Share Units		Fair Value		Share Units		Fair Value		Share Units		Fair Value
Restricted share units outstanding January 1,		717,696	$	151,212		799,129	$	166,144		696,641	$	136,905
Granted		97,140		21,113		138,567		27,733		340,957		73,953
Vested		(160,329)		(32,714)		(164,104)		(30,717)		(144,473)		(25,305)
Forfeited		(35,357)		(7,553)		(55,896)		(11,948)		(93,996)		(19,409)
Restricted share units outstanding December 31,		619,150	$	132,058		717,696	$	151,212		799,129	$	166,144

Share-Based Compensation Shares Vesting During Year

	2019		2018		2017
Amounts for the year (in 000's, except number of shares):
Fair value of vested shares on vesting date	$	33,769	$	32,317	$	31,962
Cash paid for taxes upon vesting in lieu of issuing common shares	$	12,162	$	12,347	$	14,092
Common shares issued upon vesting		96,479		97,516		82,060
Restricted share unit expense (a)	$	21,662	$	53,869	$	28,841

(a)Amounts for 2019, 2018 and 2017 include approximately $1.2 million, $1.1 million and $0.7 million, respectively, in employer taxes incurred upon vesting. Amounts for 2018 include $22.6 million, in connection with the acceleration of amortization on grants to our CEO and CFO as discussed above. Amounts for 2017 reflect a reduction in compensation expense of $4.6 million related to RSUs forfeited during the period.