Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Details)

v3.10.0.1
Stockholders' Equity (Details) - USD ($)
12 Months Ended
Jul. 31, 2018
Jul. 31, 2017
Jul. 31, 2016
Jul. 24, 2013
Dec. 31, 2014
Jan. 14, 2011
Stockholders' Equity (Details) [Line Items]            
Common Stock, Par or Stated Value Per Share (in Dollars per share) $ 0.01 $ 0.01        
Percentage of Commission Payable on Equity Offering   3.00%        
Maximum Offering Price Under Sales Agreement (in Shares)   20,000,000     20,000,000  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in Shares) 635,625 141,876 33,702      
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in Shares)       2,000,000    
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares)     5,000,000      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value $ 743,000 $ 10,530,000 $ 4,399,000      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value 1,723,000 14,510,000 6,451,000      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value $ 6,014,000 $ 1,388,000 $ 64,000      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in Shares)   4,250        
Minimum [Member]            
Stockholders' Equity (Details) [Line Items]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 2 years          
Maximum [Member]            
Stockholders' Equity (Details) [Line Items]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 4 years          
2011 Plan [Member]            
Stockholders' Equity (Details) [Line Items]            
Share Based Compensation Arrangement by Share Based Payment Award Restricted Stock Units (in Shares)           3,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares) 1,930,200          
Common Stock [Member]            
Stockholders' Equity (Details) [Line Items]            
Authorized Common Stock that may be Issued and Sold Under Sales Agreement   $ 19,200,000        
Securities That May Be Sold Under The Agreement   $ 150,000,000        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in Shares) 294,726 141,876 33,702      
Treasury Stock, Shares, Acquired (in Shares) 340,898          
Stock Issued During Period, Shares, Employee Benefit Plan (in Shares) 37,580 91,541 160,352      
Payments of Stock Issuance Costs $ 782,000 $ 724,000 $ 709,000      
Common Stock [Member] | Restricted Stock [Member]            
Stockholders' Equity (Details) [Line Items]            
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value $ 24,000 $ 44,000 $ 46,000      
Treasury Stock [Member]            
Stockholders' Equity (Details) [Line Items]            
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in Shares) 340,898          
Treasury Stock, Shares, Acquired (in Shares) 106,911          
Treasury Stock, Value $ 1,014,000          
Stock Issued During Period, Shares, Treasury Stock Reissued (in Shares) 106,911          
Stock Issued During Period, Shares, Employee Benefit Plan (in Shares) (106,911)          
Executive Officers [Member] | Performance Shares [Member]            
Stockholders' Equity (Details) [Line Items]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 3 years          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value $ 141          
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in Shares) 32,000