Share-Based Compensation and Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2017

Restricted stock [Member]

Share-Based Compensation and Benefit Plans

Summary of activity of share-based compensation

	For the Three Months Ended   June 30,				For the Six Months Ended   June 30,
	2017		2016		2017		2016
Compensation expense for shares issued under the ESPP	$	573	$	549	$	1,114	$	1,072
Income tax benefit from compensation expense related to shares issued under the ESPP	218		205		424		400
Compensation expense for restricted shares awarded	414		322		1,092		641
Income tax benefit from compensation expense related to restricted awards	$	158	$	120	$	416	$	239

Stock option [Member]

Share-Based Compensation and Benefit Plans

Summary of stock options

	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2016	2,800		$	104.90
Granted	209		264.45
Exercised	(418	)	48.77
Forfeited	(16	)	203.83
Outstanding at June 30, 2017	2,575		$	126.41
Exercisable at June 30, 2017	1,761		$	75.20

Black-Scholes option pricing model

	For the Six Months Ended   June 30,
	2017		2016
Risk free interest rate	2.02	%	1.52	%
Expected life	5.6 Years		5.7 Years
Expected volatility	22.3	%	22.4	%
Expected dividend yield	—	%	—	%

Summary of activity of share-based compensation

	For the Three Months Ended   June 30,				For the Six Months Ended   June 30,
	2017		2016		2017		2016
Compensation expense for stock options awarded	$	3,938	$	3,804	$	8,147	$	8,140
Income tax benefit from compensation expense related to stock options	1,500		1,421		3,103		3,040