Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Stock-based Awards

The following table summarizes the stock options activity under the 2010 Plan and 2019 Plan for the six months ended June 30, 2020:

	Stock Options Outstanding
	(in thousands, except year and per share data)
	Shares Subject to Options Outstanding	Weighted- Average Exercise Price per Option		Weighted- Average Remaining Contractual Terms (in years)	Aggregate Intrinsic Value
Balances as of December 31, 2019	21,191	$	2.30	7.4	$	312,720
Options granted	1,700	$	17.93
Options exercised	(2,618)	$	1.69		$	54,791
Options canceled/forfeited/expired	(188)	$	2.56
Balances as of June 30, 2020	20,085	$	3.70	7.4	$	647,698
Vested and expected to vest as of June 30, 2020	20,085	$	3.70	7.4	$	647,698
Exercisable as of June 30, 2020	18,386	$	2.39	7.2	$	617,064

Schedule of Assumptions Used to Determine the Fair Value of Stock Options Granted

The weighted-average assumptions used to determine the fair value of stock options granted during the periods presented were as follows:

	Six months ended June 30,
	2020		2019
Expected term (in years)	6.0		6.2
Expected volatility	40.3	%	40.3	%
Risk-free interest rate	0.7	%	2.3	%
Dividend yield	—		—

Schedule of Restricted Stock Units Activity

Restricted stock and RSU activity for the six months ended June 30, 2020 was as follows:

	Restricted Stock and RSUs	Weighted-Average Grant Date Fair Value
	(in thousands, except per share data)
Unvested and outstanding as of December 31, 2019	6,508	$	11.08
Granted - RSUs	1,987	$	20.61
Granted - Restricted stock	841	$	17.06
Vested - RSUs	(1,068)	$	10.17
Forfeited	(278)	$	11.35
Unvested as of June 30, 2020	7,990	$	13.04
Vested and not yet released	9	$	9.07
Outstanding as of June 30, 2020	7,999	$	13.04

Schedule of Fair Value Assumptions for Employee Stock Purchase Plan

The weighted-average assumptions used to determine the fair value of the ESPP during the periods presented were as follows:

	Six months ended June 30,
	2020		2019
Expected term (in years)	0.6		N/A
Risk-free interest rate	1.2	%	N/A
Expected volatility	45.8	%	N/A
Dividend yield	—		N/A

Schedule of Stock-based Compensation Expense

The following table sets forth the total stock-based compensation expense included in the Company’s condensed consolidated statements of operations:

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
	(in thousands)
Cost of revenue	$	280	$	34	$	547	$	66
Sales and marketing	3,608		275		6,771		554
Research and development	5,374		406		11,464		823
General and administrative	3,187		329		6,564		658
Total stock-based compensation expense	$	12,449	$	1,044	$	25,346	$	2,101