Stockholders' Equity and Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Stockholders Equity And Stock Based Compensation [Abstract]

Summary of Number of Shares of Common Stock Reserved

The number of shares of common stock reserved for the vesting of RSUs and exercise of common stock options are as follows (in thousands):

	December 31, 2019		December 31, 2018
RSUs		1,529		1,983
Common stock options		1,494		1,840
		3,023		3,823

Schedule of Stock Compensation Expense by Award Type

The following two tables show stock compensation expense by award type and where the stock compensation expense is recorded in the Company’s consolidated statements of operations:

	Year Ended December 31,
	2019		2018		2017
	( in thousands)
Options	$	5,078	$	5,108	$	4,948
ESPP		4,866		2,833		1,233
RSUs		87,810		68,320		41,136
Total stock-based compensation	$	97,754	$	76,261	$	47,317

Effect of Stock-Based Compensation on Income by Line Item

The following two tables show stock compensation expense by award type and where the stock compensation expense is recorded in the Company’s consolidated statements of operations:

	2019		2018		2017
	(in thousands)
Cost of revenue, subscription	$	3,127	$	1,476	$	658
Cost of revenue, service		2,829		2,924		2,327
Research and development		33,748		23,328		12,816
Sales and marketing		36,599		31,099		19,016
General and administrative		21,451		17,434		12,500
Total stock-based compensation	$	97,754	$	76,261	$	47,317

Schedule of Assumptions Used for Estimation of Fair Value of Options Granted to Employees

Stock Options —The fair value of employee options is estimated on the date of each grant using the Black-Scholes option-pricing model with the following assumptions:

	Year Ended December 31,
	2019		2018		2017
Risk-free interest rate (%)	1.95-2.55		2.62-2.85		1.74-2.09
Expected term (years)	5.50-6.02		5.06-6.42		5.18-6.21
Volatility (%)	39.46-41.41		41.34-43.55		39.4-43.7
Expected dividends		—		—		—

Summary of Stock Option Activity

The stock option activity for the year ended December 31, 2019 is as follows:

	Options (in thousands)			Weighted- Average Exercise Price		Weighted- Average Remaining Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding—January 1, 2019		1,840		$	23.89		4.6	$	187,342
Granted	106				160.15
Exercised		(416	)	20.95
Forfeited/expired		(36	)	77.31
Outstanding—December 31, 2019		1,494			33.09		4.0	$	187,398
Options vested or expected to vest—December 31, 2019		1,494		$	33.09		4.0	$	187,398
Options exercisable—December 31, 2019		1,294		$	19.63		3.3	$	179,688

Summary of Activity Related to RSUs

The following table summarizes the activity related to RSUs for the year ended December 31, 2019:

	RSUs Outstanding
	Shares (in thousands)			Weighted- Average Grant Date Fair Value Per Share
Unvested and outstanding at January 1, 2019		1,983		$	83.67
Granted		772			158.86
Vested		(1,011	)		84.34
Canceled		(215	)		95.64
Unvested and outstanding at December 31, 2019		1,529		$	119.46

Summary of Activity Related to Employee Stock Purchase Plan

The following table summarizes the activity related to ESPP:

	Shares Issued (in thousands)		Weighted- Average Purchase Price		Total Cash Proceeds (in thousands)
2019		116	$	123.69	$	14,383
2018		148	$	80.21	$	11,863
2017		94	$	38.83	$	3,635