Share-Based Compensation and Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2018

Restricted stock [Member]

Share-Based Compensation and Benefit Plans

Summary of activity of share-based compensation

	For the Three Months Ended   March 31,
	2018		2017
Compensation expense for shares issued under the ESPP	$	543	$	541
Income tax benefit from compensation expense related to shares issued under the ESPP	136		205
Compensation expense for restricted shares awarded	341		678
Income tax benefit from compensation expense related to restricted awards	$	86	$	257

Stock option [Member]

Share-Based Compensation and Benefit Plans

Summary of stock options

	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2017	2,364		$	137.08
Granted	201		252.78
Exercised	(155	)	71.47
Forfeited	(9	)	252.78
Outstanding at March 31, 2018	2,401		$	150.59
Exercisable at March 31, 2018	1,507		$	91.61

Black-Scholes option pricing model

	For the Three Months Ended   March 31,
	2018		2017
Risk free interest rate	2.58	%	2.09	%
Expected life	6.3 Years		5.9 Years
Expected volatility	23.7	%	22.3	%
Expected dividend yield	—	%	—	%

Summary of activity of share-based compensation

	For the Three Months Ended   March 31,
	2018		2017
Compensation expense for stock options awarded	$	4,292	$	4,209
Income tax benefit from compensation expense related to stock options	1,078		1,593
Weighted-average grant-date fair value of options awarded	$	75.42	$	70.34