Quarterly report pursuant to Section 13 or 15(d)

Warrants - Summary of Warrants Outstanding (Detail)

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Warrants - Summary of Warrants Outstanding (Detail) - $ / shares
3 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Class of Warrant or Right [Line Items]      
Warrants Outstanding 2,177,425 2,177,425 17,559
Class One [Member]      
Class of Warrant or Right [Line Items]      
Exercise Price $ 3.10    
Warrants Outstanding 48,387    
Expiration Date Sep. 19, 2022    
Class Two [Member]      
Class of Warrant or Right [Line Items]      
Exercise Price $ 3.10    
Warrants Outstanding 462,106    
Expiration Date May 10, 2024    
Class Three [Member]      
Class of Warrant or Right [Line Items]      
Exercise Price $ 3.10    
Warrants Outstanding 602,414    
Expiration Date Jul. 25, 2024    
Class Four [Member]      
Class of Warrant or Right [Line Items]      
Exercise Price $ 3.10    
Warrants Outstanding 1,064,518    
Expiration Date Nov. 08, 2024