Stock Benefit Plans and Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

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, 2019		4,215		$	3.27
Granted		71		$	6.64
Exercised		(241	)	$	2.33			$	2,253
Forfeited		(94	)	$	10.44
Outstanding at December 31, 2020		3,951		$	3.21		6.93	$	45,320
Options vested and exercisable at    December 31, 2020		2,837		$	3.26		6.70	$	32,570
Options vested and expected to vest at    December 31, 2020		3,951		$	3.21		6.93	$	45,320

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, 2019		6,727		$	2.17
Awarded		3,964		$	4.87
Vested		(2,363	)	$	3.52
Forfeited		(112	)	$	4.13
Unvested at December 31, 2020		8,216		$	3.13		1.99

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,
	2020		2019
Risk-free interest rate	0.12% - 1.58%		1.58% - 2.50%
Expected dividend yield		—		—
Expected term (years)		0.50		0.50
Volatility	54.96%-102.50%		49.78%-82.08%

Summary of Common Stock Reserved for Future Issuance

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

	December 31, 2020
Warrants outstanding		24,881
Authorized for future grant under the Plans		5,015
Authorized for future grant under the Management    Objective Strategic Incentive Plan		345
Authorized for future grant under the Distributor and Development Services plans		7,780
Stock options outstanding		3,951
Unvested restricted stock awards		8,216
Employee stock purchase plan		216
Series A convertible preferred stock		29
		50,433