Annual report pursuant to Section 13 and 15(d)

Financial Instruments - Additional Information (Detail)

v3.19.1
Financial Instruments - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
May 17, 2017
Apr. 30, 2018
May 31, 2017
Dec. 31, 2018
Dec. 31, 2016
Jun. 25, 2018
Dec. 31, 2017
Nov. 21, 2017
May 16, 2017
Mar. 31, 2017
Schedule of Available-for-sale Securities [Line Items]                    
Marketable securities maturity period       1 year            
Warrants to purchase common stock       1,297,151     1,524,573      
Shares price per share           $ 18.00   $ 23    
Bridge Loan [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Warrants to purchase common stock 313,440               240,000  
Fair value of warrant       $ 6,534            
Initial Public Offering [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Shares price per share $ 15.00       $ 15.00          
Acacia [Member] | Bridge Loan [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Warrants to purchase common stock 120,000                  
Convertible Notes Payable [Member] | Acacia [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Number of warrants issued         3          
Warrants maturity period         4 years          
Fair value of warrant         $ 841          
Acacia Note Warrants [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Number of warrants issued       154,311            
Warrants maturity period       4 years            
Warrants to purchase common stock         51,437          
Fair value of warrant         $ 841          
Warrant exercise price       $ 13.6088            
Primary Warrant [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Fair value of warrant         $ 8,064          
Primary Warrant [Member] | Acacia [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Warrants maturity period         5 years          
Warrant, percentage 10.00%                  
Amended Primary and Acacia Note Warrants [Member] | Initial Public Offering [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Warrant exercise price                   $ 13.6088
10% Warrant [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Number of warrants issued       809,400            
Warrants maturity period       5 years            
Warrant exercise price       $ 13.6088            
10% Warrant [Member] | Acacia [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Warrants maturity period     5 years              
Warrants to purchase common stock     809,400              
Warrant exercise price     $ 13.6088              
Warrant, percentage     10.00%              
10% Warrant [Member] | Acacia [Member] | Fair Value, Inputs, Level 3 [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Fair value of warrant     $ 5,790              
Warrant, percentage     10.00%              
April 2018 Warrant [Member]                    
Schedule of Available-for-sale Securities [Line Items]                    
Number of warrants issued       20,000            
Warrants maturity period   5 years   5 years            
Warrants to purchase common stock   20,000   20,000            
Warrant exercise price   $ 11.73   $ 11.7300