Stock Benefit Plans and Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Summary of Compensation Cost for Stock-Based Compensation Arrangements

The compensation cost that has been included in the Company’s consolidated statements of operations for all stock-based compensation arrangements is detailed as follows (in thousands):

	Year Ended December 31,
	2022		2021		2020
Cost of sales	$	2,597	$	737	$	512
Research and development		5,016		4,056		2,114
Sales, general and administrative		32,943		31,657		15,033
Total	$	40,556	$	36,450	$	17,659

Summary of Stock Option Activity

A summary of the Company’s stock option activity under the Plans and related information is as follows (in thousands, except as indicated and per share data):

	Shares			Weighted average exercise price		Weighted average remaining contractual term (in years)		Aggregate intrinsic value
Outstanding at December 31, 2021		3,351		$	3.50
Exercised		(378	)		2.84
Forfeited		(57	)		13.83
Outstanding at December 31, 2022		2,916		$	3.38		4.58	$	26,783
Options vested and expected to vest at    December 31, 2022		2,916		$	3.38		4.58	$	26,783
Options exercisable at    December 31, 2022		2,849		$	3.22		4.51	$	26,550

Summary of Weighted Average Assumptions Used to Compute Stock-Based Compensation Costs for Stock Options Granted

The weighted average assumptions used to compute the stock-based compensation costs for the stock options granted during the years ended December 31, 2021 and 2020 are as follows:

	Year Ended December 31,
		2021			2020
Risk-free interest rate			0.84	%		1.03	%
Expected dividend yield			—			—
Weighted average expected life (years)			6.07			6.08
Volatility			87.38	%		84.00	%

Summary of Information about Restricted Stock Awards, Restricted Stock Units and Performance-Based Restricted Units Activity

The following table summarizes information about the restricted stock units and performance-based restricted units activity (in thousands, except as indicated and per share data):

	Shares			Weighted average grant date fair value		Weighted average remaining recognition period (in years)
Unvested at December 31, 2021		8,703		$	6.34
Awarded		3,909			8.13
Vested		(3,316	)		4.68
Forfeited		(763	)		6.30
Unvested at December 31, 2022		8,533		$	6.63		1.43

Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Stock Purchase Rights under ESPP

The Company estimates the fair value of shares issued to employees under the ESPP using the Black-Scholes option-pricing model. The assumptions used to estimate the fair value of stock purchase rights under the ESPP are as follows:

	Year Ended December 31,
	2022		2021		2020
Risk-free interest rate	0.07% - 4.54%		0.04% - 0.12%		0.12% - 1.58%
Expected dividend yield		—		—		—
Expected term (years)	0.50 - 0.60			0.50		0.50
Volatility	50.29% - 64.53%		49.98% - 78.37%		54.96% - 102.5%

Summary of Common Stock Reserved for Future Issuance

Common stock reserved for future issuance consists of the following (in thousands):

	December 31, 2022
Stock options outstanding		2,916
Unvested restricted stock units		8,533
Employee stock purchase plan		119
Senior convertible notes		17,246
Warrants outstanding		15,491
Authorized for future grant under the Distributor and    Development Services plans		281
Authorized for future grant under the Management    Objective Strategic Incentive Plan		274
Authorized for future grant under the Company    Equity plans		1,269
		46,129