Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2021

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Stock Option Activity

The following is a summary of stock option activity for the current year period:

	Stock Options
	Number of Shares			Weighted Average Exercise Price		Aggregate Intrinsic Value (in thousands)		Weighted Average Remaining Contractual Term (in years)
Outstanding at December 31, 2020		15,100,142		$	16.07	$	143,156		6.9
Granted		2,472,878		$	21.99
Exercised		(641,252	)	$	14.93
Forfeited		(641,986	)	$	19.50
Expired		(12,117	)	$	13.91
Outstanding, vested and expected to vest at March 31, 2021		16,277,665		$	16.88	$	39,588		7.0
Vested and exercisable at March 31, 2021		10,607,672		$	15.46	$	32,604		5.9

Summary of Estimated Fair Value of Stock Options Granted Using Weighted-average Assumptions

Except for the Executive Option Grant discussed above, the Company used the Black-Scholes-Merton option pricing model to estimate the fair value of stock options granted using the following weighted-average assumptions:

	Three Months Ended March 31,
	2021	2020
Expected life (in years)	5.8	5.8
Risk-free interest rate	0.7%	1.4%
Volatility	52%	48%
Dividend yield	—%	—%
Fair value of common stock	$21.99	$21.32

Summary of Stock-based Compensation Expense Recognized in Financial Statements

Stock-based compensation expense recognized in the condensed consolidated financial statements is as follows:

	Three Months Ended March 31,
(in thousands)	2021		2020
Cost of revenue	$	1,482	$	960
Research and development		9,497		6,457
Sales and marketing		5,778		4,343
General and administrative		6,842		5,742
Stock-based compensation expense, net of amounts capitalized		23,599		17,502
Capitalized stock-based compensation expense		559		776
Stock-based compensation expense	$	24,158	$	18,278

Summary of Unamortized Stock-based Compensation

As of March 31, 2021, unamortized stock-based compensation was as follows:

	Unrecognized stock-based compensation (in thousands)		Weighted average vesting period (in years)
Restricted stock units	$	158,993		2.5
Stock options		48,201		2.4
Restricted stock awards		6,659		2.5
ESPP		5,084		1.5
Total unrecognized stock-based compensation	$	218,937

Restricted Stock Units

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Restricted Stock Units and Restricted Stock Awards

The following is a summary of restricted stock units for the current year period:

	Restricted Stock Units
	Number of Shares			Weighted Average Grant-Date Fair Value		Weighted Average Remaining Contractual Term (in years)
Unvested at December 31, 2020		7,000,855		$	17.72		1.1
Granted		2,764,398		$	26.89
Vested		(966,637	)	$	16.29
Forfeited/cancelled		(469,916	)	$	18.65
Unvested at March 31, 2021		8,328,700		$	20.88		1.2

Restricted Stock Awards

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Restricted Stock Units and Restricted Stock Awards

The following is a summary of restricted stock awards for the current year period:

	Restricted Stock Awards
	Number of Shares			Weighted Average Grant-Date Fair Value		Weighted Average Remaining Contractual Term (in years)
Unvested at December 31, 2020		102,460		$	18.30		1.2
Granted		274,417		$	26.89
Vested		(17,077	)	$	18.30
Forfeited/cancelled		(64,823	)	$	26.89
Unvested at March 31, 2021		294,977		$	24.40		2.3