XML 44 R53.htm IDEA: XBRL DOCUMENT v2.4.0.6
Weighted Average Assumptions Used in Black-Scholes Option Pricing Model (Detail)
12 Months Ended
Jan. 31, 2013
Jan. 31, 2012
Jan. 31, 2011
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]      
Expected stock price volatility   68.50% 64.10%
Expected stock price volatility, Minimum 58.20%    
Expected stock price volatility, Maximum 68.50%    
Risk-free interest rate   1.20%  
Risk-free interest rate, minimum 0.30%   2.30%
Risk-free interest rate, maximum 0.60%   3.40%
Expected dividend yield 0.00% 0.00% 0.00%
Directors and officers
     
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]      
Expected lives of options 7 years 7 years 7 years
Employees
     
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]      
Expected lives of options 6 years 6 years 6 years