Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Stock-Based Compensation [Abstract]

Schedule Of Assumptions Used To Estimate Fair Value Of Stock Options

	For the year ended December 31,
	2016	2015	2014
Risk free interest rate	1.11% - 1.43%	1.21% - 1.46%	1.15% - 1.37%
Dividend yield	0.0%	0.0%	0.0%
Expected volatility	20.0%	20.0%	22.0%
Expected lives	4.7 years	4.6 years	4.4 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, 2013	2,979	$	48.30
Granted	1,121	$	95.51
Exercised	(780)	$	36.34
Canceled	(44)	$	81.21
Outstanding at December 31, 2014	3,276	$	66.85
Granted	1,076	$	124.24
Exercised	(495)	$	51.58
Canceled	(63)	$	93.74
Outstanding at December 31, 2015	3,794	$	84.66
Granted	1,357	$	96.64
Exercised	(603)	$	46.03
Canceled	(101)	$	105.37
Outstanding at December 31, 2016	4,447	$	93.09	4.6	$	66,625
Exercisable at December 31, 2016	1,633	$	77.54	3.3	$	47,345
Unvested at December 31, 2016	2,814	$	102.11	5.3	$	19,280

Additional Information Regarding Options Outstanding And Exercisable

	Options Outstanding				Options Exercisable
		Weighted Average	Weighted			Weighted
		Remaining	Average			Average
Range	Outstanding	Contractual Life	Exercise Price		Exercisable	Exercise Price
	(in thousands)	(in years)			(in thousands)
$0.00 - $40.00	92	0.6	$	35.06	92	$	35.06
$40.01 - $70.00	435	1.9	$	46.11	435	$	46.11
$70.01 - $100.00	2,897	4.9	$	91.00	851	$	84.18
$100.01 - $130.00	1,023	5.2	$	124.20	255	$	124.19
	4,447				1,633

Activity Of Options Outstanding Not Yet Vested

		Weighted-
		Average
	Number	Fair Value
	of Shares	Per Share
	(in thousands)
Unvested as of December 31, 2015	2,445	$	21.43
Shares granted	1,357	$	19.19
Vesting during period	(897)	$	20.64
Forfeited	(91)	$	20.82
Unvested as of December 31, 2016	2,814	$	20.62

Company's Restricted Stock Unit Activity

		Weighted-
		Average
		Grant Date
	Number of	Fair Value per
	Shares	Share
	(in thousands)
Outstanding at December 31, 2015	277	$	97.14
Granted	137	$	96.76
Vested	(114)	$	84.44
Forfeited/canceled	(9)	$	103.15
Outstanding at December 31, 2016	291	$	101.74

Schedule Of Non-Cash Compensation Expense

		For the year ended December 31,
	2016		2015		2014
	(in thousands)
Cost of revenues	$	418	$	405	$	386
Selling, general and administrative		32,497		28,342		22,285
Total cost of non-cash compensation included
in loss before provision for income taxes		32,915		28,747		22,671
Amount of income tax recognized in earnings		—		—		—
Amount charged against loss	$	32,915	$	28,747	$	22,671