Annual report pursuant to Section 13 and 15(d)

Liquidity and Management Plans - Additional Information (Detail)

v3.8.0.1
Liquidity and Management Plans - Additional Information (Detail) - USD ($)
1 Months Ended 3 Months Ended 12 Months Ended
Jan. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Liquidity And Management Plans [Line Items]                          
Engineering product development                   $ 1,154,009      
Net income (loss)   $ (11,236,477) $ (12,748,248) $ (12,919,010) $ (12,473,140) $ (14,611,234) $ (10,125,063) $ (10,284,555) $ (10,796,542) (49,376,875) $ (45,817,394) $ (27,561,702)  
Net cash provided by (used in) operating activities                   (34,430,298) (33,062,247) (20,005,734)  
Proceeds from issuance of common stock                   14,932,547 34,788,311    
Cash and cash equivalents, at carrying value, total   $ 12,795,254       $ 31,258,637       $ 12,795,254 $ 31,258,637 $ 29,872,564 $ 31,494,592
Subsequent Event [Member]                          
Liquidity And Management Plans [Line Items]                          
Stock issued during period, shares, new issues $ 38,999,989                        
Common stock, discount on shares $ 1,000,000