Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Stock-Based Compensation [Abstract]

Schedule of Assumptions Used to Estimate Fair Value of Stock Options

	For the year ended December 31,
	2018	2017	2016
Risk free interest rate	2.57% - 2.92%	1.70% - 1.97%	1.11% - 1.43%
Dividend yield	0.7%	0.0%	0.0%
Expected volatility	21.6%	20.0%	20.0%
Expected lives	4.6 years	4.6 years	4.7 years

Summary of Stock Option Activity

		Weighted-		Weighted-Average
		Average		Remaining
	Number	Exercise Price		Contractual	Aggregate
	of Shares	Per Share		Life (in years)	Intrinsic Value
Outstanding at December 31, 2015	3,794	$	84.66
Granted	1,357	$	96.64
Exercised	(603)	$	46.03
Forfeited/canceled	(101)	$	105.37
Outstanding at December 31, 2016	4,447	$	93.09
Granted	1,171	$	115.41
Exercised	(709)	$	80.73
Forfeited/canceled	(67)	$	105.81
Outstanding at December 31, 2017	4,842	$	100.12
Granted	941	$	156.55
Exercised	(926)	$	81.73
Forfeited/canceled	(41)	$	123.98
Outstanding at December 31, 2018	4,816	$	114.48	4.2	$	228,248
Exercisable at December 31, 2018	2,162	$	100.15	3.0	$	133,490
Unvested at December 31, 2018	2,654	$	126.17	5.1	$	94,758

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 - $90.00	406	1.0	$	68.96	406	$	68.96
$90.01 - $110.00	1,609	3.5	$	96.29	983	$	96.08
$110.01 - $145.00	1,871	4.4	$	119.15	773	$	121.69
$145.01 - $175.00	930	6.2	$	156.55	—	$	0.00
	4,816				2,162

Summary of Activity of Options Outstanding not yet Vested

		Weighted-
		Average
	Number	Fair Value
	of Shares	Per Share
	(in thousands)
Unvested as of December 31, 2017	2,860	$	22.08
Shares granted	941	$	33.01
Vesting during period	(1,104)	$	21.74
Forfeited/canceled	(43)	$	26.32
Unvested as of December 31, 2018	2,654	$	26.05

Summary of Restricted Stock Unit Activity

		Weighted-Average
	Number of	Grant Date Fair
	Shares	Value per Share
	(in thousands)
Outstanding at December 31, 2017	328	$	110.20
Granted	138	$	156.61
Vested	(129)	$	110.93
Forfeited/canceled	(13)	$	135.22
Outstanding at December 31, 2018	324	$	128.69

Schedule of Non-Cash Compensation Expense

		For the year ended December 31,
	2018		2017		2016
	(in thousands)
Cost of revenues	$	1,182	$	1,013	$	418
Selling, general and administrative		41,145		37,236		32,497
Total cost of non-cash compensation included
in loss before provision for income taxes		42,327		38,249		32,915
Amount of income tax recognized in earnings		—		—		—
Amount charged against loss	$	42,327	$	38,249	$	32,915