Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2021

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

Schedule of performance-based awards

Period Granted	Options Granted	RSUs Granted	Options Vested	RSUs Vested	Milestone	Valuation Method
(in thousands)
Q1 2019	200	300	169	260	(1)	Monte-Carlo Simulation
Q2 2019	—	188	—	81	(2)	Fair Market Value
Q3 2019	—	50	—	38	(1)	Monte-Carlo Simulation
Q1 2020	150	300	94	216	(1)	Monte-Carlo Simulation
Q1 2020	—	436	—	404	(3)	Fair Market Value
Q1 2020	129	—	129	—	(3)	Black-Scholes-Merton
Q2 2020	—	21	—	21	(3)	Fair Market Value
Q3 2020	10	—	10	—	(4)	Black-Scholes-Merton
Q3 2020	—	27	—	13	(3)	Fair Market Value
Q4 2020	—	32	—	6	(1)	Monte-Carlo Simulation
Q4 2020	—	22	—	2	(5)	Fair Market Value
Q1 2021	150	125	—	—	(1)	Monte-Carlo Simulation
Q1 2021	—	279	—	10	(3)	Fair Market Value
Q2 2021	163	—	—	—	(1)	Monte-Carlo Simulation
Q2 2021	29	—	—	—	(3)	Black-Scholes-Merton
Q2 2021	—	7	—	—	(3)	Fair Market Value

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(1) The awards will vest based on the achievement of certain values of the Company’s common stock at multiple thresholds within certain periods and are contingent upon the completion of requisite service through the date of such vesting.

(2) The vesting of the awards will be triggered after the end of the achievement milestone, as measured by the Company.

(3) The awards will vest based on achievement of a revenue target and are contingent upon the completion of requisite service through the date of such vesting.

(4) The awards vest based on achievement of a reimbursement target.

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(5) The awards will vest based on achievement of certain revenue and recruiting targets.

Summary of stock option activity

	Outstanding Options
					Weighted-
			Weighted-		Average
	Shares		Average		Remaining	Aggregate
	Available for	Number of	Exercise		Contractual	Intrinsic
(in thousands, except for contractual life and exercise price)	Grant	Shares	Price		Life	Value
					(in years)
Balance at December 31, 2020	3,197	6,707	$	11.19	6.04	$	592,468
Additional shares authorized	3,446	—
Options granted	(390)	390	$	104.01
Options exercised	—	(782)	$	8.73
Options forfeited/cancelled	31	(31)	$	13.80
RSUs granted	(1,355)	—
RSUs forfeited/cancelled	164	—
Balance at June 30, 2021	5,093	6,284	$	17.25	5.93	$	605,986
Exercisable at June 30, 2021		4,823	$	9.93	5.23	$	499,683
Vested and expected to vest at June 30, 2021		6,194	$	16.90	5.90	$	599,432

Restricted stock units

		Weighted-
		Average
		Grant Date
(in thousands, except for grant date fair value)	Shares	Fair Value
Balance at December 31, 2020	4,188	$	34.02
Granted	1,355	$	103.67
Vested	(1,387)	$	26.50
Cancelled/forfeited	(164)	$	41.33
Balance at June 30, 2021	3,992	$	59.73

Summary of stock-based compensation expenses

	Three months ended June 30,
	2021						2020
	Employee		Non-Employee		Total		Employee		Non-Employee		Total
	(in thousands)
Cost of revenues	$	1,275	$	—	$	1,275	$	441	$	—	$	441
Research and development		6,276		340		6,616		2,631		282		2,913
Selling, general and administrative		27,146		66		27,212		8,527		76		8,603
Total	$	34,697	$	406	$	35,103	$	11,599	$	358	$	11,957

	Six months ended June 30,
	2021						2020
	Employee		Non-Employee		Total		Employee		Non-Employee		Total
	(in thousands)
Cost of revenues	$	1,983	$	—	$	1,983	$	755	$	—	$	755
Research and development		9,926		564		10,490		4,313		442		4,755
Selling, general and administrative		45,751		111		45,862		13,779		85		13,864
Total	$	57,660	$	675	$	58,335	$	18,847	$	527	$	19,374

Performance-based awards

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

Schedule of assumptions used in valuation of fair value

	June 30,
	2021
Risk-free interest rate		0.80	%	—	1.42	%
Expected dividend yield					0.00	%
Expected volatility					60	%
Expected term (years)		7.25		—	10.00

Employee stock options

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

Schedule of assumptions used in valuation of fair value

	Three months ended June 30,								Six months ended June 30,
	2021					2020			2021					2020
Expected term (years)	5.11		—	10.00			10.00		5.11		—	10.00		5.27		—	10.00
Expected volatility	56.01	%	—	63.30	%		53.94	%	55.33	%	—	63.30	%	49.94	%	—	58.53	%
Expected dividend rate				0.00	%		0.00	%				0.00	%				0.00	%
Risk-free interest rate	0.81	%	—	1.67	%		0.71	%	0.81	%	—	1.67	%	0.44	%	—	1.70	%