Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Summary of Series B Preferred Stock and Accretion of Dividends

The following table summarizes Series B Preferred Stock and the accretion of dividends activity for the year ended December 31, 2019 (in thousands):

	Tranche 1		Tranche 2		Total
Series B Preferred Stock
Balance at December 31, 2018	$	12,600	$	8,233	$	20,833
Cumulative dividends on Series B preferred stock		630		412		1,042
Balance at December 31, 2019	$	13,230	$	8,645	$	21,875
Number of Common Shares Issuable Upon Conversion
Balance at December 31, 2018		3,150		2,058		5,208
Cumulative dividends on Series B preferred stock		158		103		261
Balance at December 31, 2019		3,308		2,161		5,469

Summary of Outstanding Warrants Issued by Company

Below is a summary of outstanding warrants issued by the Company as of December 31, 2019:

Warrant Type	Number of Shares Issuable Upon Exercise		Weighted Average Exercise Price		Issue Date	Expiration Date
EWB Warrant		40,000		3.64	February 8, 2017	February 8, 2022
VLL7 and VLL8 Warrants		580,000		2.00	February 8, 2017	February 8, 2022
Total		620,000

Summary of Common Stock Reserved for Future Issuance

Common Stock Reserved for Future Issuance

Common stock reserved for future issuance as of December 31, 2019 was as follows:

Exercise of outstanding stock options, vesting of RSUs, and issuance of RSUs vested but not released	1,913,152
Employee Stock Purchase Plan	293,888
Shares of common stock available for grant under the 2011 Plan	436,366
Warrants to purchase common stock	620,000
Shares of common stock issuable on conversion of Series B preferred stock	7,541,449
Total	10,804,855