Quarterly report pursuant to Section 13 or 15(d)

Liquidity and Management Plans - Additional Information (Detail)

v3.10.0.1
Liquidity and Management Plans - Additional Information (Detail) - USD ($)
1 Months Ended 3 Months Ended 6 Months Ended
Jul. 31, 2017
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Dec. 31, 2016
Liquidity And Management Plans [Line Items]              
Engineering product development   $ 205,773 $ 299,506 $ 230,773 $ 874,874    
Net income (loss)   (12,298,371) (12,919,010) (25,741,828) (25,392,150)    
Net cash provided by (used in) operating activities       (15,371,126) (18,956,003)    
Proceeds from issuance of common stock       38,846,815      
Cash and cash equivalents, at carrying value, total   37,076,181 13,084,360 37,076,181 13,084,360 $ 12,795,254 $ 31,258,637
At-the-Market [Member]              
Liquidity And Management Plans [Line Items]              
Proceeds from issuance of common stock       38,846,815      
Private Placements [Member]              
Liquidity And Management Plans [Line Items]              
Proceeds from issuance of common stock $ 14,932,547            
Technology Service [Member]              
Liquidity And Management Plans [Line Items]              
Engineering product development   $ 205,773 $ 299,506 $ 230,773 $ 874,874