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Other Current Assets - Additional Information (Detail) - USD ($)
Dec. 31, 2018
Dec. 31, 2017
Other Assets Current [Line Items]    
Prepaid expenses $ 478,560 $ 471,686
Directors and Officers Insurance [Member]    
Other Assets Current [Line Items]    
Prepaid expenses 388,137 316,795
Marine Insurance [Member]    
Other Assets Current [Line Items]    
Prepaid expenses 40,119 67,447
Professional Services [Member]    
Other Assets Current [Line Items]    
Prepaid expenses 38,674 75,784
Other Insurances [Member]    
Other Assets Current [Line Items]    
Prepaid expenses $ 11,630 $ 11,660