Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Summary of Series B Preferred Stock and Accretion of Dividends

The following table summarizes Series B convertible preferred stock and the accretion of dividends activity for the years ended December 31, 2020 and 2019 (in thousands):

	December 31,
	2020		2019
Series B Convertible Preferred Stock:
Balance at beginning of period	$	21,875	$	20,833
Cumulative dividends on Series B convertible preferred stock		1,094		1,042
Balance at end of period	$	22,969	$	21,875
Number of Common Shares Issuable Upon Conversion
Number of shares at beginning of period		5,469		5,208
Cumulative dividends on Series B convertible preferred stock		273		261
Number of shares at end of period		5,742		5,469

Summary of Outstanding Warrants Issued by Company

Below is a summary of outstanding warrants issued by the Company as of December 31, 2020:

Warrant Type	Number of Shares Issuable Upon Exercise		Weighted Average Exercise Price		Issue Date	Expiration Date
East West Bank Warrant		40,000	$	3.50	February 8, 2017	February 8, 2023
April 21 Funds Warrants		275,000		3.50	May 5, 2020	May 5, 2023
Total		315,000

Summary of Common Stock Reserved for Future Issuance

Common Stock Reserved for Future Issuance

Common stock reserved for future issuance as of December 31, 2020 was as follows:

Exercise of outstanding stock options, vesting of restricted stock units ("RSU"), vesting of performance stock    units ("PSU"), and issuance of RSUs vested but not released	1,731,432
Employee Stock Purchase Plan	293,888
Shares of common stock available for grant under the 2011 Plan	1,055,419
Warrants to purchase common stock	315,000
Shares of common stock issuable upon conversion of Series B convertible preferred stock	7,541,449
Total	10,937,188