Share-Based Compensation and Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2018

Share-based Compensation [Abstract]

Summary Of Share Incentive Plans

A summary of activity under our share incentive plans for the year ended December 31, 2018 is shown below:

	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		232,478		82.81
Exercised/Vested	(78,972	)	63.35		(316,668	)	75.66
Forfeited	—		—		(25,027	)	79.83
Total options and nonvested share awards outstanding at December 31, 2018	—		$	—	390,681		$	79.82

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

	Year Ended December 31, 2018	Year Ended December 31, 2017	Year Ended December 31, 2016
Weighted average fair value of options granted	$4.11	$5.25	$6.71
Expected volatility	15.1%	18.9%	18.0%
Risk-free interest rate	2.0%	1.3%	0.9%
Expected dividend yield	3.3%	5.5%	3.8%
Expected life	1 year	2 years	3 years

Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity [Table Text Block]

The following table presents information related to our ESPP:

	2018		2017		2016
Shares purchased	15,330		18,986		20,797
Weighted average fair value of shares purchased	$	90.93	$	89.89	$	82.33
Expense recorded (in millions)	$	0.2	$	0.3	$	0.4

Temporary Equity [Table Text Block]

The following table summarizes the eligible share award activity for the twelve months ended December 31:

(in thousands)	2018			2017
Temporary equity:
Balance at inception/beginning of period	$	77,230		$	77,037
Change in classification	16,407			13,388
Change in redemption value	(669		)	10,038
Diversification of share awards (429 and 261 shares during December 31, 2018 and 2017, respectively)	(40,294		)	(23,233		)
Balance at December 31	$	52,674		$	77,230