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Common Stock - Additional Information (Detail)
12 Months Ended
Oct. 16, 2018
Dec. 31, 2018
USD ($)
shares
Dec. 31, 2017
shares
Class Of Stock [Line Items]      
Common stock, shares authorized | shares   100,000,000 100,000,000
Voting power per share   One  
Common stock, dividends declared | $   $ 0  
Common Stock [Member]      
Class Of Stock [Line Items]      
Reverse stock split ratio 1-for-6    
Conversion ratio 0.01667