Share-based Compensation and Non-Qualified Deferred Compensation Plan (Tables)

3 Months Ended

Mar. 31, 2018

Share-based Compensation [Abstract]

Schedule of Share Based Compensation Shares Authorized Under Stock Option Plans By Exercise Price Range And Intrinsic Value

The following table summarizes outstanding share options, all of which were exercisable, at March 31, 2018:

	Options Outstanding and Exercisable (1)
Exercise Prices	Number	Weighted Average Price
$75.17	15,388	$	75.17
$78.55	9,994	78.55
$80.89 - $85.05	27,476	82.84
Total options	52,858	$	79.79

(1) The aggregate intrinsic value of options outstanding and exercisable at March 31, 2018 was $0.2 million. The aggregate intrinsic value was calculated as the excess, if any, between our closing share price of $84.18 per share on March 31, 2018 and the strike price of the underlying award.

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The following assumptions were used for the reload options granted during the three months ended March 31, 2018:

	Three Months Ended March 31, 2018
Weighted average fair value of options granted	4.11
Expected volatility	15.1%
Risk-free interest rate	2.0%
Expected dividend yield	3.3%
Expected life	1 year

Summary of Share Incentive Plans

The following table summarizes activity under our share incentive plans for the three months ended March 31, 2018:

	Options Outstanding		Weighted Average Exercise / Grant Price		Nonvested Share Awards Outstanding		Weighted Average Exercise /  Grant Price
Options and nonvested share awards outstanding at December 31, 2017	68,978		$	61.15	499,898		$	75.80
Granted	9,994		78.55		211,417		82.65
Exercised/Vested	(26,114	)	30.06		(298,419	)	75.22
Forfeited	—		—		(12,650	)	79.16
Total options and nonvested share awards outstanding at March 31, 2018	52,858		$	79.79	400,246		$	79.74

Summary of non-qualified deferred compensation share award activity

The following table summarizes the eligible share award activity for the three months ended March 31, 2018:

(in thousands)	Three Months Ended March 31, 2018
Temporary equity:
Balance at December 31, 2017	$	77,230
Change in classification	5,250
Change in redemption value	(6,306		)
Balance at March 31, 2018	$	76,174