Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Shares (Detail)

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Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Shares (Detail) - shares
3 Months Ended 6 Months Ended
Jun. 30, 2022
Jun. 30, 2021
Jun. 30, 2022
Jun. 30, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 27,139,760 15,133,722 27,139,760 15,133,722
Outstanding stock options        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 2,129,002 1,607,080 2,129,002 1,607,080
Outstanding restricted stock units        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 1,024,929 134,774 1,024,929 134,774
Warrants to purchase common stock associated with December 2019 Public Offering | Warrant        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 0 4,472,205 0 4,472,205
December 2020 Public Offering Series 2 | Warrant        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 6,800,000 6,800,000 6,800,000 6,800,000
April 2022 Public Offering | Warrant        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 15,000,000 0 15,000,000 0
March 2018 Public Offering Series 2 | Warrant        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 798,810 798,810 798,810 798,810
Warrants to purchase common stock associated with Loan Agreement | Warrant        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 198,819 170,410 198,819 170,410
Warrants to purchase common stock associated with Solar loan agreement | Warrant        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 0 12,243 0 12,243
Common stock associated with March 2019 Notes        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 1,138,200 1,138,200 1,138,200 1,138,200
Warrants to purchase common stock associated with Danforth | Warrant        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive securities (in shares) 50,000 0 50,000 0