Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Stock-based compensation expense

Stock-based compensation expense included in the consolidated statements of operations was as follows:

	Year Ended December 31,
(in thousands)	2022		2021		2020
Cost of revenue	$	8,369	$	4,446	$	3,158
Sales and marketing	49,383		29,410		19,842
Research and development	31,499		20,593		14,794
General and administrative	31,382		24,956		21,779
Total stock-based compensation expense	$	120,633	$	79,405	$	59,573

Summary of RSU and PSUs

A summary of our restricted stock, RSU and PSU activity is presented below:

	Restricted Stock			RSUs			PSUs
(in thousands, except for per share data)	Number of Shares	Weighted Average Grant Date Fair Value		Number of Shares	Weighted Average Grant Date Fair Value		Number of Shares	Weighted Average Grant Date Fair Value
Unvested balance at December 31, 2019	495	$	4.25	2,894	$	26.34	—	$	—
Granted	—	—		3,570	28.23		—	—
Vested	(396)	4.25		(1,504)	25.37		—	—
Forfeited	—	—		(470)	26.68		—	—
Unvested balance at December 31, 2020	99	4.25		4,490	28.13		—	—
Granted	—	—		3,842	43.57		—	—
Vested	(99)	4.25		(1,872)	28.14		—	—
Forfeited	—	—		(679)	33.64		—	—
Unvested balance at December 31, 2021	—	—		5,781	37.74		—	—
Granted	—	—		4,653	45.83		209	44.97
Vested	—	—		(2,510)	36.47		—	—
Forfeited	—	—		(1,030)	40.45		(13)	44.97
Unvested balance at December 31, 2022	—	—		6,894	43.26		196	44.97

Stock option activity

A summary of our stock option activity is below:

(in thousands, except for per share data and years)	Number of Shares	Weighted Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2019	12,939	$	8.38	7.1	$	201,608
Granted	—	—
Exercised	(2,956)	7.34			73,277
Forfeited/canceled	(542)	10.80
Outstanding at December 31, 2020	9,441	8.56		6.4	412,547
Granted	—	—
Exercised	(2,671)	6.84			111,256
Forfeited/canceled	(39)	14.96
Outstanding at December 31, 2021	6,731	9.21		5.5	308,677
Granted	—	—
Exercised	(1,174)	9.98			47,880
Forfeited/canceled	(72)	16.15
Outstanding and exercisable at December 31, 2022	5,485	8.96		4.5	160,135

ESPP valuation assumptions

The fair value of the 2018 ESPP purchase rights was estimated on the offering or modification dates using a Black-Scholes option-pricing model and the following assumptions:

	Year Ended December 31,
	2022	2021	2020
Expected term (in years)	0.5 — 2.0	0.5 — 2.0	0.5 — 2.0
Expected volatility	42.8% — 61.0%	37.2% — 59.4%	41.6% — 60.1%
Risk-free interest rate	0.1% — 3.4%	0.1% — 0.2%	0.1% — 0.9%
Expected dividend yield	—	—	—