Quarterly report pursuant to Section 13 or 15(d)

Offerings of Common Stock and Warrants and At-the-Market Offering Program (Details)

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Offerings of Common Stock and Warrants and At-the-Market Offering Program (Details) - USD ($)
3 Months Ended 6 Months Ended 27 Months Ended
Oct. 21, 2016
Oct. 18, 2016
Apr. 22, 2016
Apr. 19, 2016
Aug. 28, 2015
Sep. 30, 2017
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Aug. 31, 2017
Number of common stock shares available to accredited investors   3,600,000                
Share price of common stock sold (in dollars per share)   $ 1.20                
Loss on adjustment of exercise price           $ 657,000 $ 657,000      
Net proceeds from offering of common stock and warrants $ 6,800,000   $ 13,100,000       3,987,000 $ 13,113,000    
Number of common stock shares available in public offering       2,700,000            
Beneficial ownership of common stock resulting from purchase of stock in public offering (as a percent)       4.99%            
Number of warrants or shares of common stock to be sold to purchase common stock       2            
Aggregate offering price for at-the-market offering program             $ 12,200,000      
Common stock sold (in shares)           2,400,000 5,800,000   13,100,000  
Net proceeds from sale of the common stock, after deducting fees and other offering expenses (in dollars)           $ 1,400,000 $ 4,000,000   $ 16,800,000  
Common stock commissions paid           45,000 100,000   $ 500,000  
Maximum                    
Aggregate offering price for at-the-market offering program         $ 30,000,000          
Series A Warrants                    
Number of shares of common stock that could be purchased with warrants       4,100,000            
Exercise price (in dollars per share)   $ 1.34   $ 3.50           $ 0.65
Loss on adjustment of exercise price           $ 700,000 $ 700,000      
Number of warrants or shares of common stock to be sold to purchase common stock       1            
Number of shares of common stock purchased with each warrant       1            
Length of time from issue date until warrants are exercisable       6 months            
Length of time from exercise date until warrants expire       5 years            
Outstanding warrants (in shares)           10,407,500 10,407,500   10,407,500  
Series A Warrants | Maximum                    
Number of shares of common stock that could be purchased with warrants   6,300,000                
Series B Warrants                    
Number of shares of common stock that could be purchased with warrants   2,700,000                
Exercise price (in dollars per share)   $ 1.20   $ 3.48            
Exercise price pre-funded at closing (in dollars per share)   1.19                
Exercise price, payable upon exercise (in dollars per share)   $ 0.01                
Number of warrants or shares of common stock to be sold to purchase common stock       2            
Length of time from exercise date until warrants expire       9 months            
Outstanding warrants (in shares)           0 0   0  
Series B Warrants | Maximum                    
Number of shares of common stock that could be purchased with warrants       5,500,000