Quarterly report pursuant to Section 13 or 15(d)

Warrants - Summary of Warrant Activity (Detail)

v3.19.1
Warrants - Summary of Warrant Activity (Detail) - $ / shares
3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Class of Warrant or Right [Line Items]    
Warrants, Beginning balance 7,371,925 2,177,425
Warrants, Granted 19,166,668 14,700,000
Warrants, Exercised 0 (9,505,500)
Warrants, Expired 0 0
Warrants, Ending balance 26,538,593 7,371,925
Weighted Average [Member]    
Class of Warrant or Right [Line Items]    
Weighted Average Price, Beginning balance $ 1.74 $ 3.10
Weighted Average Price, Granted 0.83 1.00
Weighted Average Price, Exercised 0 1.00
Weighted Average Price, Expired 0 0
Weighted Average Price, Ending balance $ 1.08 $ 1.74