Stock Benefit Plans and Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

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, 2020		3,951		$	3.21
Granted		85			13.62
Exercised		(569	)		2.63
Forfeited		(116	)		5.28
Outstanding at December 31, 2021		3,351		$	3.50		6.03	$	27,619
Options vested and exercisable at    December 31, 2021		2,973		$	3.24		5.86	$	25,162
Options vested and expected to vest at    December 31, 2021		3,351		$	3.50		6.03	$	27,619

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 awards, 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, 2020		8,216		$	3.13
Awarded		3,980			12.79
Vested		(2,824	)		3.88
Forfeited		(669	)		4.01
Unvested at December 31, 2021		8,703		$	6.34		1.66

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 options granted and stock purchase rights under the ESPP are as follows:

	Year Ended December 31,
	2021		2020
Risk-free interest rate	0.04% - 0.12%		0.12% - 1.58%
Expected dividend yield		—		—
Expected term (years)		0.50		0.50
Volatility	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, 2021
Stock options outstanding		3,351
Unvested restricted stock units		8,703
Employee stock purchase plan		547
Series A convertible preferred stock		29
Senior convertible notes		17,246
Warrants outstanding		20,184
Authorized for future grant under the Distributor and    Development Services plans		445
Authorized for future grant under the Management    Objective Strategic Incentive Plan		365
Authorized for future grant under the Company    Equity plans		4,025
		54,895