Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Grants Outside of 2000 and 2017 Plans and Stockholder Rights Plan (Details)

v3.19.2
Stockholders' Equity - Grants Outside of 2000 and 2017 Plans and Stockholder Rights Plan (Details)
 12 Months Ended 43 Months Ended
May 06, 2019
Vote
$ / shares
Feb. 04, 2019
USD ($)
$ / shares
shares
Apr. 13, 2018
$ / shares
shares
Mar. 31, 2019
USD ($)
$ / shares
shares
Mar. 31, 2018
USD ($)
$ / shares
shares
Mar. 31, 2019
USD ($)
$ / shares
shares
Jun. 07, 2018
USD ($)
Aug. 28, 2015
USD ($)
Stockholder Rights Plan                
Common stock, par value (in dollars per share)       $ 0.001 $ 0.001 $ 0.001    
Preferred stock, par value (in dollars per share)       0.001 0.001 0.001    
Offerings of Common Stock and Warrants and At-the-Market Offering Program                
Common stock, par value (in dollars per share)       $ 0.001 $ 0.001 $ 0.001    
Loss on adjustment of exercise price | $         $ 741,000      
Net proceeds from offering of common stock and warrants | $       $ 11,098,000 $ 13,581,000      
Common stock sold (in shares) | shares     3,806,243          
Series A Warrants                
Offerings of Common Stock and Warrants and At-the-Market Offering Program                
Exercise price (in dollars per share)     $ 0.60          
Outstanding warrants (in shares) | shares       2,718,750   2,718,750    
Warrants Exercised | shares     5,760,000          
Class of Warrant or Right, Exercise Price of Warrants or Rights     $ 0.60          
Series A Warrants, Exercise Price 2.55                
Offerings of Common Stock and Warrants and At-the-Market Offering Program                
Exercise price (in dollars per share)       $ 2.55   $ 2.55    
Class of Warrant or Right, Exercise Price of Warrants or Rights       2.55   2.55    
Series A Warrants, Exercise Price 1.34                
Offerings of Common Stock and Warrants and At-the-Market Offering Program                
Exercise price (in dollars per share)       0.57   0.57    
Initial exercise price (in dollars per share)       $ 1.34   1.34    
Issued warrants (in shares) | shares       540,000        
Class of Warrant or Right, Exercise Price of Warrants or Rights       $ 0.57   $ 0.57    
Series B Warrants                
Offerings of Common Stock and Warrants and At-the-Market Offering Program                
Outstanding warrants (in shares) | shares       0   0    
Warrants                
Stockholder Rights Plan                
Common stock, par value (in dollars per share)   $ 0.001            
Offerings of Common Stock and Warrants and At-the-Market Offering Program                
Warrant purchase | shares   4,046,337            
Exercise price (in dollars per share)   $ 0.8859            
Common stock, par value (in dollars per share)   $ 0.001            
Purchase price | $   $ 150,000            
Value of the Warrant | $   $ 2,300,000            
Class of Warrant or Right, Exercise Price of Warrants or Rights   $ 0.8859            
August 2015 Sales Agreement                
Offerings of Common Stock and Warrants and At-the-Market Offering Program                
Net proceeds from sale of the common stock, after deducting fees and other offering expenses (in dollars) | $       $ 4,000,000   $ 28,600,000    
Common stock sold (in shares) | shares       2,800,000   26,000,000    
Common stock commissions paid | $       $ 100,000   $ 800,000    
June 2018 Sales Agreement                
Offerings of Common Stock and Warrants and At-the-Market Offering Program                
Net proceeds from sale of the common stock, after deducting fees and other offering expenses (in dollars) | $       6,900,000        
Aggregate offering price for at-the-market offering program | $       $ 17,800,000   $ 17,800,000    
Common stock sold (in shares) | shares       7,600,000        
Common stock commissions paid | $       $ 200,000        
Maximum | August 2015 Sales Agreement                
Offerings of Common Stock and Warrants and At-the-Market Offering Program                
Aggregate offering price for at-the-market offering program | $               $ 30,000,000
Maximum | June 2018 Sales Agreement                
Offerings of Common Stock and Warrants and At-the-Market Offering Program                
Aggregate offering price for at-the-market offering program | $             $ 25,000,000  
Stock options                
Class of Stock [Line Items]                
Options outstanding (in shares) | shares       174,944 212,392 174,944    
Portion vesting one year after the issuance date (as a percent)       25.00%        
Portion vesting on first day of each month after one year from the issuance date (as a percent)       2.083%        
Expiration Term       10 years        
Vesting period       4 years        
Restricted stock units                
Class of Stock [Line Items]                
Options outstanding (in shares) | shares       2,400,000 2,000,000 2,400,000    
Series B Junior Participating Preferred Stock                
Stockholder Rights Plan                
Preferred stock conversion basis 0.001              
Purchase price (in dollars per share) $ 5.22              
Preferred stock dividend minimum if declared $ 1.00              
Preferred stock rights ratio over common stock 1,000              
Number of votes per share | Vote 1,000              
Ratio of consideration received in event of conversion or exchange transaction 1,000              
Series B Junior Participating Preferred Stock | Minimum                
Stockholder Rights Plan                
Beneficial ownership of common stock (as a percent) 4.90%