Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2020

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)
Balances as of December 31, 2019	6,111,561		20,859,326		$	124.28
New Shares Authorized	17,500,000		—		—
Granted	(1,498,232	)	1,498,232		412.45
Exercised	—		(2,988,359	)	67.58
Expired	—		(188	)	13.38
Balances as of September 30, 2020	22,113,329		19,369,011		$	155.32
Vested and exercisable as of September 30, 2020			19,369,011		$	155.32

Summary of Amounts Related to Option Exercises

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

	Three Months Ended				Nine Months Ended
	September 30, 2020		September 30, 2019		September 30, 2020		September 30, 2019
	(in thousands)
Total intrinsic value of options exercised	$	321,859	$	119,439	$	1,067,241	$	513,213
Cash received from options exercised	68,665		11,989		201,419		56,857

Summary of Assumptions Used to Value Stock Option Grants Using Lattice-Binomial Model

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

	Three Months Ended						Nine Months Ended
	September 30, 2020			September 30, 2019			September 30, 2020			September 30, 2019
Dividend yield	—		%	—		%	—		%	—		%
Expected volatility	45		%	38		%	37% - 45%			38% - 41%
Risk-free interest rate	0.67		%	1.92		%	0.67% - 1.71%			1.92% - 2.74%
Suboptimal exercise factor	3.62			3.19			3.34 - 3.62			3.07 - 3.19
Weighted-average fair value (per share)	$	264		$	154		$	205		$	165
Total stock-based compensation expense (in thousands)	$	106,357		$	100,262		$	307,586		$	305,310
Total income tax impact on provision (in thousands)	$	24,292		$	22,679		$	68,435		$	69,152