Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Issued and Outstanding Shares - Additional Information (Detail)

v3.21.2
Common Stock - Issued and Outstanding Shares - Additional Information (Detail) - USD ($)
 3 Months Ended 9 Months Ended 49 Months Ended
May 27, 2021
Dec. 07, 2020
Aug. 06, 2020
Jul. 01, 2020
Apr. 28, 2020
Mar. 12, 2020
May 22, 2018
Sep. 14, 2017
Sep. 30, 2021
Jun. 30, 2021
Mar. 31, 2021
Sep. 30, 2020
Jun. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock, par value                 $ 0.001         $ 0.001   $ 0.001 $ 0.001
Common stock, shares issued                 9,453,542         9,453,542   9,453,542 6,111,735
Proceeds from exercise of warrants                           $ 339,000 $ 3,080,000    
Stock option exercises, Shares                 0     0   0 0    
Restricted stock unit settlements                 231     236   231 236    
Common Stock [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock, shares issued                   2,149 2,965            
Restricted stock unit settlements                 145     128          
April 2020 Private Placement [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock, shares issued         280,782                        
Warrants to purchase shares of common stock         0.75                        
Warrants to purchase shares of common stock, offering price per share         $ 6.60                        
Gross proceeds from issuance of common stock         $ 1,900,000                        
Proceeds from exercise of warrants         $ 1,600,000                        
Percentage of exercise price exceeds in measurement period                           300.00%      
Average daily trading volume for measurement period                           $ 500,000      
Number of required consecutive days weighted average trading price for cancelation or recall of warrants                           30 days      
April 2020 Private Placement [Member] | Common Stock [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock, shares issued                         280,782        
April 2020 Private Placement [Member] | Placement Agent [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Exercise price per unit of warrant         $ 7.59                        
Number of common shares issuable conversion of warrants         25,270                        
Direct Offering [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Gross proceeds from issuance of common stock       $ 6,000,000.0                          
Placement agent fees and offering expenses       700,000                          
Proceeds from issuance of common stock       $ 5,300,000                     $ 5,307,000    
Direct Offering [Member] | Common Stock [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock, shares issued       731,707               731,707          
Common stock, price per share       $ 8.20                          
August 2020 Public Offering [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Gross proceeds from issuance of common stock     $ 7,500,000                            
Proceeds from issuance of common stock     6,800,000                       6,822,000    
Underwriting discounts and commissions and offering expenses     $ 700,000                            
August 2020 Public Offering [Member] | Common Stock [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock, shares issued     569,043                 569,043          
Common stock, price per share     $ 10.50                            
Underwriters Over-Allotment Option Exercise [Member] | Common Stock [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock, shares issued 428,571 322,500 92,856                            
December 2020 Public Offering [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Gross proceeds from issuance of common stock   $ 17,300,000                              
Proceeds from issuance of common stock   15,800,000                              
Underwriting discounts and commissions and offering expenses   $ 1,500,000                              
December 2020 Public Offering [Member] | Common Stock [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock, shares issued   2,472,500                              
Common stock, price per share   $ 7.00                              
December 2020 Public Offering [Member] | Representative's Warrant [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Number of common shares issuable conversion of warrants   50,000                              
Common stock, price per share   $ 8.75                              
Adjustments to additional paid in capital Other   $ 300,000                              
Warrant exercisable term   5 years                              
May 2021 Public Offering [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Gross proceeds from issuance of common stock $ 23,000,000.0                                
Proceeds from issuance of common stock 21,300,000                                
Underwriting discounts and commissions and offering expenses $ 1,700,000                                
May 2021 Public Offering [Member] | Common Stock [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock, shares issued 3,285,714                                
Common stock, price per share $ 7.00                                
Subscription Agreements Executed on April 27, 2020 [Member] | April 2020 Private Placement [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Exercise price per unit of warrant                 $ 7.24         $ 7.24   $ 7.24  
Subscription Agreements Executed on April 28, 2020 [Member] | April 2020 Private Placement [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Exercise price per unit of warrant                 $ 7.32         $ 7.32   $ 7.32  
Pre-Funded Warrant [Member] | August 2020 Public Offering [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Number of common shares issuable conversion of warrants     142,857                            
Pre-funded warrant, offering price per share     $ 10.499                            
Pre-Funded Warrant [Member] | August 2020 Public Offering [Member] | Common Stock [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Exercise price per unit of warrant     $ 0.001                            
Number of days of prior notice to achieve not in excess percentage of common stock shares owned by warrant holder     61 days                            
Pre-Funded Warrant [Member] | August 2020 Public Offering [Member] | Common Stock [Member] | Minimum [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Percentage of shares of common stock owned by warrant holder     9.99%                            
Pre-Funded Warrant [Member] | August 2020 Public Offering [Member] | Common Stock [Member] | Maximum [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Percentage of shares of common stock owned by warrant holder     19.99%                            
LPC [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock value right to sell, maximum           $ 11,000,000.0                      
Common stock, par value           $ 0.001                      
Minimum percentage of common stock shares outstanding authorized to sell             20.00%                    
Initial purchase of common stock                               1,644  
Common stock, shares issued               617                  
Payments related to expense reimbursement           $ 100,000                      
Common stock, shares issued                 0         0   27,868  
Gross proceeds                               $ 4,400,000  
Offering expenses                               500,000  
Common stock available for sale under offering                 $ 6,600,000         $ 6,600,000   $ 6,600,000  
LPC [Member] | Purchase Agreement [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Common stock, purchase price               $ 1.00                  
Additional common stock value right to sell, maximum               $ 10,000,000.0                  
Additional purchase of common stock, maximum               7,500                  
Offering expenses                             $ 14,000    
LPC [Member] | Units [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Initial purchase of common stock               1,644                  
Common stock, purchase price               $ 608.00                  
Purchase agreement, description                           Unit consisting of (a) one share of our common stock and (b) one warrant to purchase one-quarter of a share of common stock at an exercise price of $699.20 per share, or Warrant. Each Warrant became exercisable six months following the issuance date until the date that is five years and six months after the issuance date and is subject to customary adjustments.      
Exercise price per unit of warrant               $ 699.20                  
Initial purchase of units consisting of common stock and warrants issued               $ 1,000,000.0                  
LPC [Member] | Other Units [Member]                                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                                  
Number of warrants issued               0