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Equity Financing - Additional Information (Detail)
 1 Months Ended 3 Months Ended 9 Months Ended
Aug. 16, 2022
USD ($)
$ / shares
Aug. 31, 2022
USD ($)
$ / shares
shares
Jan. 31, 2021
USD ($)
$ / shares
shares
Dec. 31, 2020
USD ($)
$ / shares
shares
Sep. 30, 2019
USD ($)
$ / shares
shares
Jun. 30, 2019
USD ($)
$ / shares
shares
Jun. 30, 2018
USD ($)
$ / shares
shares
Mar. 31, 2018
USD ($)
$ / shares
shares
Sep. 30, 2022
USD ($)
$ / shares
Sep. 30, 2021
USD ($)
Sep. 30, 2022
USD ($)
$ / shares
Sep. 30, 2021
USD ($)
Dec. 31, 2021
$ / shares
Jan. 28, 2021
Class Of Warrant Or Right [Line Items]                            
Common stock, par value | $ / shares                 $ 0.001   $ 0.001   $ 0.001  
Offering costs allocated to common stock warrant liability and expensed | $                 $ 314,000 $ 0 $ 314,000 $ 769,000    
Maximum [Member]                            
Class Of Warrant Or Right [Line Items]                            
Proceeds from issuance, aggregate offering prices | $                     $ 50,000,000.0      
March 2018 Purchase Agreement [Member]                            
Class Of Warrant Or Right [Line Items]                            
Shares of common stock issued               1,201,634            
Warrant issued, shares of common stock called by warrant               1,282,832            
Warrants issued, exercise price | $ / shares               $ 10.7258            
August 2022 Purchase Agreement [Member]                            
Class Of Warrant Or Right [Line Items]                            
Shares of common stock issued   2,450,000                        
Offering closing period   Aug. 16, 2022                        
August 2022 Purchase Agreement [Member] | Pre Funded Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant   2,272,506                        
Warrants issued, exercise price | $ / shares   $ 0.0001                        
August 2022 Purchase Agreement [Member] | Preferred Investment Options [Member]                            
Class Of Warrant Or Right [Line Items]                            
Shares of common stock issued   4,722,506                        
Exercise price | $ / shares   $ 0.93376                        
Proceeds from issuance of common stock pre-funded warrants and preferred investment options | $   $ 5,000,000.0                        
Warrants expiration period   5 years                        
December 2020 Purchase Agreement [Member]                            
Class Of Warrant Or Right [Line Items]                            
Shares of common stock issued       2,618,658                    
Proceeds from issuance of common stock and warrants gross | $       $ 8,000,000.0                    
Offering closing period       Dec. 22, 2020                    
December 2020 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant       2,618,658                    
Warrants issued, exercise price | $ / shares       $ 3.00                    
Warrants expiration period       5 years 6 months                    
September 2019 Purchase Agreement [Member]                            
Class Of Warrant Or Right [Line Items]                            
Shares of common stock issued         1,318,828                  
Proceeds from issuance of common stock and warrants gross | $         $ 10,000,000.0                  
Offering closing period         Sep. 05, 2019                  
September 2019 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant         659,414                  
Warrants issued, exercise price | $ / shares         $ 7.52                  
Warrants expiration period         5 years 6 months                  
June 2019 Purchase Agreement [Member]                            
Class Of Warrant Or Right [Line Items]                            
Shares of common stock issued           1,489,575                
Proceeds from issuance of common stock and warrants gross | $           $ 7,500,000                
Offering closing period           Jun. 14, 2019                
June 2019 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant           1,489,575                
Warrants issued, exercise price | $ / shares           $ 5.00                
Warrants expiration period           5 years 6 months                
June 2018 Purchase Agreement [Member]                            
Class Of Warrant Or Right [Line Items]                            
Shares of common stock issued             1,392,345              
Proceeds from issuance of common stock and warrants gross | $             $ 14,000,000.0              
Offering closing period             Jun. 14, 2018              
June 2018 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant             1,392,345              
Warrants issued, exercise price | $ / shares             $ 9.94              
Warrants expiration period             5 years 6 months              
June 2018 Placement Agent Warrants [Member] | June 2018 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant             69,617              
Warrants issued, exercise price | $ / shares             $ 12.568              
Warrant, exercisable term             5 years              
June 2019 Placement Agent Warrants [Member] | June 2019 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant           74,479                
Warrants issued, exercise price | $ / shares           $ 6.2938                
Warrant, exercisable term           5 years                
September 2019 Placement Agent Warrants [Member] | September 2019 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant         65,942                  
Warrants issued, exercise price | $ / shares         $ 9.4781                  
Warrant, exercisable term         5 years                  
August 2022 Options and August 2022 Placement Agent Options [Member]                            
Class Of Warrant Or Right [Line Items]                            
Expected volatility 128.46%                          
Stock price | $ / shares $ 0.94                          
Risk-free interest rate 2.97%                          
Expected term 5 years                          
August 2022 Placement Agent Options [Member]                            
Class Of Warrant Or Right [Line Items]                            
Fair value assumptions, value | $ $ 191,000                          
Offering costs | $ 488,000                          
Allocation of common stock option liability expense | $ 314,000                          
Remaining offering costs allocated to common stock and offset to additional paid in capital | $ 365,000                          
August 2022 Placement Agent Options [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Offering costs | $ $ 679,000                          
August 2022 Placement Agent Options [Member] | August 2022 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant   236,125                        
Warrants issued, exercise price | $ / shares   $ 1.32                        
Warrant, exercisable term   5 years                        
December 2020 Placement Agent Warrants [Member] | December 2020 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant       130,933                    
Warrants issued, exercise price | $ / shares       $ 3.8188                    
Warrant, exercisable term       5 years                    
January 2021 Private Placement [Member] | January 2021 Purchase Agreement [Member]                            
Class Of Warrant Or Right [Line Items]                            
Shares of common stock issued     7,876,784                      
Warrant issued, shares of common stock called by warrant     3,938,392                      
Warrants issued, exercise price | $ / shares     $ 3.13                      
Proceeds from issuance of common stock and warrants gross | $     $ 25,100,000                      
Warrants expiration period     5 years 6 months                      
Remaining offering costs allocated to common stock and offset to additional paid in capital | $     $ 2,000,000.0                      
January 2021 Private Placement [Member] | January 2021 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Offering costs allocated to common stock warrant liability and expensed | $     $ 769,000                      
January 2021 Private Placement [Member] | January 2021 Purchase Agreement [Member] | Warrants [Member] | Expected Volatility [Member]                            
Class Of Warrant Or Right [Line Items]                            
Preferred investment options liability, measurement input                           1.238
January 2021 Private Placement [Member] | January 2021 Purchase Agreement [Member] | Warrants [Member] | Stock Price [Member]                            
Class Of Warrant Or Right [Line Items]                            
Preferred investment options liability, measurement input                           2.88
January 2021 Private Placement [Member] | January 2021 Purchase Agreement [Member] | Warrants [Member] | Risk-Free Interest Rate [Member]                            
Class Of Warrant Or Right [Line Items]                            
Preferred investment options liability, measurement input                           0.5
January 2021 Private Placement [Member] | January 2021 Placement Agent Warrants [Member] | January 2021 Purchase Agreement [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant     393,839                      
Warrants issued, exercise price | $ / shares     $ 3.99                      
Offering costs | $     $ 1,900,000                      
Warrant, exercisable term     5 years 6 months                      
Issuance of placement agent warrants | $     $ 942,000                      
January 2021 Private Placement [Member] | January 2021 Placement Agent Warrants [Member] | January 2021 Purchase Agreement [Member] | Warrants [Member]                            
Class Of Warrant Or Right [Line Items]                            
Offering costs | $     $ 2,800,000                      
March 2018 Private Placement [Member] | March 2018 Purchase Agreement [Member]                            
Class Of Warrant Or Right [Line Items]                            
Shares of common stock issued               300,752            
Warrant issued, shares of common stock called by warrant               300,752            
Warrants issued, exercise price | $ / shares               $ 45.75            
Proceeds from issuance of common stock and warrants gross | $               $ 10,000,000.0            
Warrants expiration period               5 years            
March 2018 Private Placement [Member] | March 2018 Placement Agent Warrants [Member] | March 2018 Purchase Agreement [Member]                            
Class Of Warrant Or Right [Line Items]                            
Warrant issued, shares of common stock called by warrant               15,038            
Warrants issued, exercise price | $ / shares               $ 41.5625            
Warrant, exercisable term               5 years