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Redeemable Convertible Preferred Stock - Additional Information (Detail)
 3 Months Ended
Mar. 31, 2019
USD ($)
Installment
$ / shares
shares
Mar. 31, 2018
USD ($)
shares
Dec. 31, 2018
USD ($)
$ / shares
shares
May 31, 2012
shares
Temporary Equity [Line Items]        
Redeemable convertible preferred stock, shares issued 1,000,000   1,000,000  
Accretion amount | $ $ 16,000      
Maximum        
Temporary Equity [Line Items]        
Accretion amount | $ $ 20,000 $ 20,000    
Series A Convertible Preferred Stock        
Temporary Equity [Line Items]        
Redeemable convertible preferred stock, shares issued       1,000,000
Warrants to purchase common stock       325,000
Cumulative dividends at a rate 6.00%      
Redeemable convertible preferred stock, liquidation preference per share | $ / shares $ 5.00      
Common stock issued as payment of preferred stock, shares 85,559 50,799    
Series A Convertible Preferred Stock | Scenario, Plan        
Temporary Equity [Line Items]        
Redeemable convertible preferred stock, liquidation preference per share | $ / shares $ 5.00      
Redemption price per share | $ / shares $ 5.00   $ 5.00  
Number of redemption price, accrued and unpaid dividends installment payments | Installment 36      
Annual interest rate on redemption value payable 6.00%      
Series A Convertible Preferred Stock | Accounts Payable and Other Accrued Expenses        
Temporary Equity [Line Items]        
Total accrued but unpaid dividends | $ $ 80,000   $ 80,000  
Series A Convertible Preferred Stock | Maximum | Scenario, Plan        
Temporary Equity [Line Items]        
Majority outstanding shares redeemable date Apr. 30, 2017