Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2016

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 (per share)		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Balances as of December 31, 2015	16,845,316		20,995,756		$	32.39
Granted	(835,669	)	835,669		99.67
Exercised			(348,776	)	10.02
Balances as of March 31, 2016	16,009,647		21,482,649		$	35.37	6.23	$	1,447,088
Vested and exercisable as of March 31, 2016			21,482,649		$	35.37	6.23	$	1,447,088

Summary of Amounts Related to Option Exercises

A summary of the amounts related to option exercises, is as follows:

	Three Months Ended
	March 31, 2016		March 31, 2015
	(in thousands)
Total intrinsic value of options exercised	$	31,457	$	80,838
Cash received from options exercised	$	3,536	$	10,916

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 and the valuation data, as adjusted for the Stock Split:

	Three Months Ended
	March 31, 2016			March 31, 2015
Dividend yield	—		%	—		%
Expected volatility	50		%	36		%
Risk-free interest rate	2.04		%	2.03		%
Suboptimal exercise factor	2.48			2.48
Weighted-average fair value (per share)	$	50.76		$	26.46
Total stock-based compensation expense (in thousands)	$	42,422		$	27,441
Total income tax impact on provision (in thousands)	$	15,963		$	10,392