Annual report pursuant to Section 13 and 15(d)

Stock Warrants - Schedule of Warrants Outstanding (Detail)

v3.20.1
Stock Warrants - Schedule of Warrants Outstanding (Detail) - $ / shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Aug. 01, 2014
Class of Warrant or Right [Line Items]      
Shares Underlying Outstanding Warrants 3,033,910 3,124,304  
Weighted-average exercise price per share $ 22.61 $ 23.10  
Placement Agent Warrants [Member]      
Class of Warrant or Right [Line Items]      
Shares Underlying Outstanding Warrants 18,915 18,915  
Representative's Warrant [Member]      
Class of Warrant or Right [Line Items]      
Shares Underlying Outstanding Warrants [1]   20,641  
Exercise Prices $ 75.00    
Other Warrants [Member]      
Class of Warrant or Right [Line Items]      
Shares Underlying Outstanding Warrants [2] 15,350 18,033  
Exercise Price Less Than or Equal to $20.00 [Member]      
Class of Warrant or Right [Line Items]      
Shares Underlying Outstanding Warrants 1,600,216    
Expiration Start Date Sep. 01, 2021    
Expiration End Date Jul. 25, 2022    
Exercise Price Greater Than or Equal to $ 20.00 [Member]      
Class of Warrant or Right [Line Items]      
Shares Underlying Outstanding Warrants 1,433,694    
Expiration Start Date Feb. 12, 2020    
Expiration End Date Jan. 05, 2022    
Minimum [Member] | Exercise Price Less Than or Equal to $20.00 [Member]      
Class of Warrant or Right [Line Items]      
Exercise Prices $ 20.00    
Maximum [Member] | Exercise Price Greater Than or Equal to $ 20.00 [Member]      
Class of Warrant or Right [Line Items]      
Exercise Prices $ 20.00    
Note Warrants [Member]      
Class of Warrant or Right [Line Items]      
Shares Underlying Outstanding Warrants   67,070 [3] 332,142
Exercise Prices     $ 30.00
2016 Warrants [Member]      
Class of Warrant or Right [Line Items]      
Shares Underlying Outstanding Warrants 1,400,000 1,400,000  
2017 Warrants [Member]      
Class of Warrant or Right [Line Items]      
Shares Underlying Outstanding Warrants 1,599,645 1,599,645  
[1] On August 27, 2019, the Representative’s Warrant to purchase common stock expired in accordance with its terms. The Representative’s Warrant was not exercised prior to expiration and has been terminated and is no longer exercisable.
[2] Other warrants are comprised of warrants issued prior to the Company’s IPO, generally in exchange for services rendered to the Company.
[3] During 2019 and 2018 the PIPE Warrants to purchase common stock expired in accordance with their terms. Only 553 of the PIPE Warrants were exercised prior to expiration and the remaining PIPE Warrants were terminated and are no longer exercisable.