CAPITAL STOCK - Reserved Authorized Shares of Common Stock (Details)	Dec. 31, 2019 shares
Class of Stock [Line Items]
Shares of common stock reserved for future issuance	2,660,179
Common stock options outstanding
Class of Stock [Line Items]
Shares of common stock reserved for future issuance	1,793,602
Common stock warrants
Class of Stock [Line Items]
Shares of common stock reserved for future issuance	720,982
Vical Plan | Options available for grant under the 2009 Plan
Class of Stock [Line Items]
Shares of common stock reserved for future issuance	86,584
2009 Plan | Options available for grant under the 2009 Plan
Class of Stock [Line Items]
Shares of common stock reserved for future issuance	59,011