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Loss Per Common Share - Schedule of Antidilutive Securities Excluded from computation of Earnings Per Share (Detail) - shares
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Series A Preferred Stock [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Anti-dilutive securities excluded from computation of earnings per share 177,996 622,987
Unvested Restricted Stock and Options to Purchase Common Stock [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Anti-dilutive securities excluded from computation of earnings per share 1,803,167 3,101,143
Warrants Exercisable into Common Stock [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Anti-dilutive securities excluded from computation of earnings per share 571,025 13,633,070