Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2022

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 dividend activity for the three months ended March 31, 2022 and 2021 (in thousands):

	Three Months Ended March 31,
	2022		2021
Series B Convertible Preferred Stock:
Balance at beginning of period	$	24,117	$	22,969
Cumulative dividends on Series B convertible preferred stock		298		284
Balance at end of period	$	24,415	$	23,253
Number of Common Shares Issuable Upon Conversion:
Number of shares at beginning of period		6,029		5,742
Cumulative dividends on Series B convertible preferred stock		75		71
Number of shares at end of period		6,104		5,813

Summary of Outstanding Warrants Issued by Company

Below is the summary of outstanding warrants issued by the Company as of March 31, 2022:

Warrant Type	Number of Shares Issuable Upon Exercise		Weighted Average Exercise Price		Issue Date	Expiration Date
April 21 Funds Warrants		275,000	$	3.50	May 5, 2020	May 5, 2023

Summary of Common Stock Reserved for Future Issuance

Common Stock Reserved for Future Issuance

Common stock reserved for future issuance as of March 31, 2022 was as follows:

Exercise of outstanding stock options, vesting of restricted stock units ("RSUs"), vesting of      performance stock units ("PSUs"), and issuance of RSUs vested but not released	1,448,112
Employee Stock Purchase Plan	293,888
Shares of common stock available for grant under the 2011 Plan	902,090
Warrants to purchase common stock	275,000
Shares of common stock issuable upon conversion of Series B convertible preferred stock	7,541,449
Total	10,460,539