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Organization and Operations - Additional Information (Details)
 3 Months Ended 12 Months Ended
Apr. 21, 2023
Apr. 20, 2023
$ / shares
Mar. 29, 2020
Mar. 28, 2020
May 29, 2015
USD ($)
Mar. 31, 2024
USD ($)
$ / shares
shares
Mar. 31, 2023
USD ($)
Dec. 31, 2023
USD ($)
$ / shares
shares
Dec. 31, 2022
USD ($)
$ / shares
shares
May 01, 2023
shares
Apr. 30, 2023
shares
Apr. 04, 2023
$ / shares
Dec. 31, 2021
USD ($)
Organization and Operations [Line Items]                          
Net loss           $ (3,261,000) $ (4,805,000) $ (13,316,000) $ (20,275,000)        
Accumulated deficit           (483,762,000)   (480,501,000) (467,185,000)        
Cash and cash equivalents           2,901,000   8,554,000 18,120,000        
Net cash used in operating activities           (4,513,000) (5,793,000) (12,851,000) (12,972,000)        
Stockholders' deficit           $ (4,837,000) $ 2,676,000 $ (1,348,000) $ 6,445,000       $ 10,836,000
Common stock, par value (in dollars per share) | $ / shares   $ 0.001       $ 0.001   $ 0.001 $ 0.001     $ 0.001  
Stock split conversion ratio 0.06                        
Common stock, shares issued (in shares) | shares           4,522,656   4,522,656 2,240,092 2,500,000 37,400,000    
Preferred stock, shares authorized (in shares) | shares           5,000,000   5,000,000 5,000,000        
Common stock, reverse stock split, fractional shares issued | shares           0   0          
Stock issued during period reverse stock splits, shares | shares           1,310   1,310          
Equity Incentive Plans [Member]                          
Organization and Operations [Line Items]                          
Common Stock, Capital Shares Reserved for Future Issuance | shares                   200,000 3,000,000    
Outstanding Warrants and Options [Member]                          
Organization and Operations [Line Items]                          
Common Stock, Capital Shares Reserved for Future Issuance | shares                   100,000 2,000,000    
Minimum [Member]                          
Organization and Operations [Line Items]                          
Stock split conversion ratio   0.33                      
Maximum [Member]                          
Organization and Operations [Line Items]                          
Stock split conversion ratio   0.06                      
Term Loan [Member]                          
Organization and Operations [Line Items]                          
Long term debt outstanding threshold amount               $ 800,000          
Fees amount associated with loan         $ 3,200,000 $ 3,200,000   $ 3,200,000          
Maturity date     Jun. 01, 2024 Sep. 01, 2021 May 01, 2021     Jun. 01, 2024          
Term Loan [Member] | Maximum [Member]                          
Organization and Operations [Line Items]                          
Long term debt outstanding threshold amount           $ 400,000   $ 800,000