Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2020

Stockholders' Equity Note [Abstract]

Schedule of Stock Option Activity

The following table summarizes stock option activity during the three months ended March 31, 2020:

	Shares		Weighted- Average  Exercise Price		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value
	(in thousands)				(in years)	(in thousands)
Outstanding at December 31, 2019	11,269		$	4.68	7.3	$	173,471
Granted	—		—
Exercised	(1,107	)	2.68
Cancelled/forfeited	(61	)	6.94
Outstanding at March 31, 2020	10,101		$	4.89	7.2	$	142,692
Vested and exercisable at March 31, 2020	6,443		$	3.00	6.4	$	102,947

Employee Stock Purchase Plan, Valuation Assumptions

We estimated the fair value of stock option awards using the Black-Scholes option pricing model with the following weighted-average assumptions:

	Three months ended March 31,
	2020	2019
Fair value of common stock	N/A	$10.32
Expected term (in years)	N/A	6.02
Risk-free interest rate	N/A	2.50%
Expected volatility	N/A	40.0%
Dividend yield	N/A	—%

We estimated the fair value of shares granted under the ESPP on the first date of the offering period using the Black-Scholes option pricing model with the following assumptions:

	Three months ended March 31,
	2020	2019
Fair value of common stock	$6.02	N/A
Expected term (in years)	0.50	N/A
Risk-free interest rate	1.59%	N/A
Expected volatility	43.0%	N/A
Dividend yield	—%	N/A

Schedule of Unvested Exercised Options

The activity of non-vested shares as a result of early exercise of options granted to employees and non-employees, is as follows:

	Three months ended March 31,
	2020
	(in thousands)
Beginning balance as of December 31, 2019	200
Early exercise of options	—
Vested	(37	)
Repurchased	—
Ending balance as of March 31, 2020	163

Schedule of Restricted Stock Units

The following table summarizes RSU activity during the three months ended March 31, 2020:

	Shares		Weighted- Average  Grant Date Fair Value Per Share
	(in thousands)
Nonvested RSUs as of December 31, 2019	1,641		$	20.07
Granted	1,072		20.03
Vested	—
Cancelled/forfeited	(11	)	20.04
RSUs outstanding as of March 31, 2020	2,702		$	20.04

Schedule of Stock-Based Compensation Expense

The following table summarizes the components of total stock-based compensation expense included in the accompanying Condensed Consolidated Statements of Operations:

	Three months ended March 31,
	2020		2019
	(in thousands)
Stock-based compensation expense by caption:
Cost of revenue	$	615	$	144
Research and development	1,671		432
Sales and marketing	1,483		369
General and administrative	2,560		522
Total	$	6,329	$	1,467