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Net Loss Per Share - Additional Information (Detail) - USD ($)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Dilutive securities, effect on basic earnings per share $ 0 $ 0
Stock Options and Stock Awards    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Outstanding securities excluded from the calculation of diluted net loss per share 8,946,000 8,394,000