Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Additional Information (Detail)

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Stockholders' Equity - Additional Information (Detail) - USD ($)
 3 Months Ended
Jan. 26, 2018
Jan. 25, 2018
Mar. 31, 2018
Mar. 31, 2017
Mar. 06, 2018
Stockholders Equity [Line Items]          
Compensation expense related to stock options     $ 700,000 $ 400,000  
Net impact of stock-based compensation expense to earnings per basic share     $ (0.01) $ (0.01)  
Net impact of stock-based compensation expense to earnings per diluted share     $ (0.01) $ (0.01)  
Total unrecognized compensation cost     $ 3,300,000    
Unrecognized share based compensation cost to be recognized over weighted-average period     2 years    
Reversal of share based compensation expense     $ 0 $ 400,000  
Outstanding stock options, RSUs and warrants excluded from diluted loss per share     18,800,000 22,900,000  
Western Alliance Warrant          
Stockholders Equity [Line Items]          
Initial exercise price of warrants         $ 0.47
Western Alliance Warrant | Maximum          
Stockholders Equity [Line Items]          
Warrants issued to purchase shares of common stock equal value         $ 120,000
Stock Options | Employees          
Stockholders Equity [Line Items]          
Stock options granted   1,800,000      
Awards valued per share   $ 0.42      
Options expiration period   10 years      
Options vesting description     The options vest ratably over the 36-month period, commencing on February 25, 2018.    
Share-based Compensation Arrangement by Share-based Payment Award, Monthly Ratable Award Vesting Period   36 months      
Share Based Compensation Arrangement By Share Based Payment Award, Vesting Commencement Date   Feb. 25, 2018      
Restricted Stock Units (RSUs)          
Stockholders Equity [Line Items]          
Granted     223,000    
Restricted Stock Units (RSUs) | President And Chief Executive Officer          
Stockholders Equity [Line Items]          
Awards valued per share $ 0.40        
Granted 200,000        
2002 Stock Incentive Plan          
Stockholders Equity [Line Items]          
Plan expiration date     May 05, 2019    
Common stock authorized for issuance under the 2002 Plan     15,600,000    
Common stock issued pursuant to options exercised     4,000,000    
Options and restricted stock units outstanding     10,800,000    
Options available for future grants     800,000