Share-Based Compensation and Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2019

Restricted stock [Member]

Share-Based Compensation and Benefit Plans

Summary of activity of share-based compensation

	For the Three Months Ended   September 30,				For the Nine Months Ended   September 30,
	2019		2018		2019		2018
Compensation expense for shares issued under the ESPP	$	622	$	569	$	1,831	$	1,689
Income tax benefit from compensation expense related to shares issued under the ESPP	155		141		456		418
Compensation expense for restricted shares awarded	351		339		1,038		1,031
Income tax benefit from compensation expense related to restricted awards	$	87	$	84	$	258	$	255

Stock option [Member]

Share-Based Compensation and Benefit Plans

Summary of stock options

	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2018	1,860		$	178.57
Granted	191		363.43
Exercised	(233	)	123.26
Forfeited	(21	)	261.28
Outstanding at September 30, 2019	1,797		$	204.41
Exercisable at September 30, 2019	1,185		$	159.01

Black-Scholes option pricing model

	For the Nine Months Ended   September 30,
	2019		2018
Risk free interest rate	2.34	%	2.61	%
Expected life	5.9 Years		6.0 Years
Expected volatility	25.0	%	23.9	%
Expected dividend yield	—	%	—	%

Summary of activity of share-based compensation

	For the Three Months Ended   September 30,				For the Nine Months Ended   September 30,
	2019		2018		2019		2018
Compensation expense for stock options awarded	$	4,590	$	4,084	$	13,709	$	12,424
Income tax benefit from compensation expense related to stock options	1,143		1,010		3,415		3,074