Share-Based Compensation and Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2015

Restricted stock [Member] | Employee stock purchase plan [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,
	2015		2014		2015		2014
Compensation expense for shares issued under the ESPP	$	526	$	451	$	1,513	$	1,332
Income tax benefit from compensation expense related to shares issued under the ESPP	198		167		565		493
Compensation expense for restricted shares awarded	417		652		1,227		2,114
Income tax benefit from compensation expense related to restricted awards	$	157	$	241	$	459	$	782

Stock option [Member]

Share-Based Compensation and Benefit Plans

Summary of stock options

	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2014	4,065		$	64.57
Granted	299		208.47
Exercised	(847	)	52.89
Forfeited	(88	)	90.92
Outstanding at September 30, 2015	3,429		$	79.32
Exercisable at September 30, 2015	2,323		$	50.08

Black-Scholes option pricing model

	For the Nine Months Ended   September 30,
	2015		2014
Risk free interest rate	1.54	%	1.60	%
Expected life	5.8 Years		5.3 Years
Expected volatility	22.3	%	25.0	%
Expected dividend yield	—	%	—	%

Summary of activity of share-based compensation

	For the Three Months Ended   September 30,				For the Nine Months Ended   September 30,
	2015		2014		2015		2014
Compensation expense for stock options awarded	$	4,409	$	4,184	$	13,916	$	13,978
Income tax benefit from compensation expense related to stock options	1,657		1,548		5,198		5,173