Annual report pursuant to Section 13 and 15(d)

Derivative Liability and Fair Value Measurements (Schedule of Fair Value Level 3 Warrant Liabilities) (Detail)

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Derivative Liability and Fair Value Measurements (Schedule of Fair Value Level 3 Warrant Liabilities) (Detail) - Warrant Liabilities [Member] - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Fair value $ 152,927 $ 173,131 $ 240,786
Reclassification of warrant exercises to Additional Paid-in Capital (166,800) 0 (32,911)
Change in fair value for the period of warrant derivative liability 13,873 (20,204) (34,744)
Fair value $ 0 $ 152,927 $ 173,131