Annual report pursuant to Section 13 and 15(d)

Debt Instruments (Details)

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Debt Instruments (Details) (USD $)
12 Months Ended
Jan. 31, 2013
Jan. 31, 2012
Jan. 31, 2011
May 13, 2011
Debt Instruments        
Outstanding amount $ 828,000 $ 520,000    
Cash collateral considered to be restricted cash 828,000 520,000    
Credit facility
       
Debt Instruments        
Maximum borrowings available       30,000,000
Minimum liquidity requirement 5,000,000      
Total debt issuance costs 1,000,000      
Term of credit facility agreement 4 years      
Amount of debt issuance costs that were amortized and included in interest expense 300,000 200,000 0  
Credit facility | Debt outstanding greater than or equal to $15 million
       
Debt Instruments        
Outstanding balance 15,000,000      
Non-usage charge (as a percent) 0.50%      
Credit facility | Debt outstanding less than $15 million
       
Debt Instruments        
Outstanding balance 15,000,000      
Non-usage charge (as a percent) 0.625%      
Credit facility | LIBOR
       
Debt Instruments        
Variable interest rate base LIBO      
Credit facility | LIBOR | Debt outstanding greater than or equal to $15 million
       
Debt Instruments        
Margin (as a percent) 3.00%      
Credit facility | LIBOR | Debt outstanding less than $15 million
       
Debt Instruments        
Margin (as a percent) 2.75%      
Credit facility | Alternate base rate
       
Debt Instruments        
Variable interest rate base alternate base rate      
Credit facility | Alternate base rate | Debt outstanding greater than or equal to $15 million
       
Debt Instruments        
Margin (as a percent) 2.00%      
Credit facility | Alternate base rate | Debt outstanding less than $15 million
       
Debt Instruments        
Margin (as a percent) 1.75%      
Credit facility | Federal funds effective rate
       
Debt Instruments        
Variable interest rate base federal funds      
Margin (as a percent) 0.50%      
Credit facility | Adjusted LIBO rate
       
Debt Instruments        
Variable interest rate base adjusted LIBO      
Margin (as a percent) 1.00%      
Letters of credit
       
Debt Instruments        
Maximum borrowings available       5,000,000
Outstanding amount 828,000 520,000    
Available borrowing capacity 29,170,000 29,480,000    
Cash collateral considered to be restricted cash $ 828,000 $ 520,000    
Letters of credit | Debt outstanding greater than or equal to $15 million
       
Debt Instruments        
Annual charge on outstanding amount (as a percent) 3.00%      
Letters of credit | Debt outstanding less than $15 million
       
Debt Instruments        
Annual charge on outstanding amount (as a percent) 2.75%