Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2014

Stockholders' Equity and Stock-based Compensation Disclosure [Abstract]

Summary Of Activity Related To Stock Option Plans

A summary of the activities related to the Company’s stock option plans is as follows:

			Options Outstanding
	Shares Available for Grant		Number of Shares		Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (in Years)	Aggregate Intrinsic Value (in Thousands)
Balances as of December 31, 2013	3,406,317		3,526,898		$	95.25
Granted	(265,146	)	265,146		387.16
Exercised			(484,014	)	96.93
Balances as of June 30, 2014	3,141,171		3,308,030		118.40		5.94	$	1,066,052
Vested and exercisable at June 30, 2014			3,308,030		118.40		5.94	$	1,066,052

Summary Of Assumptions Used To Value Stock Option Grants Using Lattice-Binomial Model

The following table summarizes the assumptions used to value stock option grants using the lattice-binomial model:

	Three Months Ended				Six Months Ended
	June 30, 2014		June 30, 2013		June 30, 2014		June 30, 2013
Dividend yield	—	%	—	%	—	%	—	%
Expected volatility	45	%	53	%	45% - 48%		53% - 54%
Risk-free interest rate	2.66	%	1.88	%	2.66% - 2.83%		1.87% - 1.88%
Suboptimal exercise factor	2.66 - 4.20		2.39 - 3.61		2.66 - 4.20		2.33 - 3.61