Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2017

Stock-Based Compensation [Abstract]

Schedule Of Assumptions Used To Estimate Fair Value Of Stock Options

	For the six months ended
	June 30,
	2017	2016
Risk free interest rate	1.70% - 1.97%	1.18% - 1.43%
Dividend yield	0.0%	0.0%
Expected volatility	20%	20%
Expected lives	4.6 years	4.7 years

Company's Activities With Respect To Its Stock Options

				Weighted-
		Weighted-		Average
		Average		Remaining
	Number	Exercise Price		Contractual	Aggregate
	of Shares	Per Share		Life (in years)	Intrinsic Value
Outstanding at December 31, 2016	4,447	$	93.09
Granted	1,170	$	115.38
Exercised	(480)	$	77.18
Canceled	(55)	$	105.04
Outstanding at June 30, 2017	5,082	$	99.60	4.8	$	179,390
Exercisable at June 30, 2017	2,208	$	87.49	3.5	$	104,656
Unvested at June 30, 2017	2,874	$	108.90	5.8	$	74,734

Company's Restricted Stock Unit Activity

		Weighted-
		Average
		Grant Date
	Number of	Fair Value per
	Shares	Share
	(in thousands)
Outstanding at December 31, 2016	291	$	101.74
Granted	168	$	115.75
Vested	(121)	$	98.63
Forfeited/canceled	(8)	$	108.50
Outstanding at June 30, 2017	330	$	109.85