Equity (Details) - USD ($)
$ in Thousands
 1 Months Ended 12 Months Ended
Aug. 01, 2016
Jul. 11, 2016
Jan. 16, 2015
Apr. 30, 2015
Jul. 31, 2016
Jul. 31, 2015
Jul. 31, 2014
Sep. 30, 2014
Equity (Textual)                
Common stock issued for exercises of stock options         $ 10 $ 68 $ 17  
Treasury stock, shares         40,000 42,000    
Sale of treasury stock         $ 65  
Treasury Stock [Member]                
Equity (Textual)                
Treasury stock, shares   2,030     39,963 41,723    
Sale of treasury stock   $ 52,476     $ 427,916 $ 480,392    
Treasury Stock [Member] | Officer [Member]                
Equity (Textual)                
Treasury stock, shares     4,105          
Sale of treasury stock     $ 65,003          
Class A common stock [Member] | Common Stock [Member]                
Equity (Textual)                
Common stock, voting rights         Class A common stock are entitled to three votes per share.      
Class B common stock [Member]                
Equity (Textual)                
Common stock, voting rights         Class B common stock are entitled to one-tenth of a vote per share.      
Issuance of shares, Description         Effective October 17, 2016, the Company will issue to Jonas a grant of 120,000 shares to vest as to 60,000 shares on October 17, 2016 and 20,000 on each of October 18, 2017, October 17, 2018 and October 16, 2019.      
Class B common stock [Member] | Dividends [Member]                
Equity (Textual)                
Dividend declared       $ 5,647,342        
Amount paid to minority shareholders       875,338        
Unpaid dividends       4,772,004        
Class B common stock [Member] | Davidi Jonas [Member]                
Equity (Textual)                
Common stock issued for compensation, Shares         60,000      
Class B common stock [Member] | Officer [Member]                
Equity (Textual)                
Common stock issued for compensation, Shares         108,000      
Class B common stock [Member] | Consultant [Member]                
Equity (Textual)                
Common stock issued for compensation, Shares         1,250      
Class B common stock [Member] | Consultant [Member] | Subsequent Event [Member]                
Equity (Textual)                
Common stock issued for compensation, Shares 1,250              
Class B common stock [Member] | Two Employees [Member]                
Equity (Textual)                
Common stock issued for compensation, Shares         36,000      
Class B common stock [Member] | Non employee directors [Member]                
Equity (Textual)                
Common stock issued for compensation, Shares         24,000      
Class B common stock [Member] | Officers, directors and consultants [Member]                
Equity (Textual)                
Common stock issued for compensation, Shares             311,226  
Class B common stock [Member] | Directors and officers [Member]                
Equity (Textual)                
Common stock issued for compensation, Shares           264,500    
Class B common stock [Member] | Employee [Member]                
Equity (Textual)                
Common stock issued for compensation, Shares         56,000      
Class B common stock [Member] | IDT[Member]                
Equity (Textual)                
Retirement of common stock issued to former employees of IDT Corporation, Shares             3,550  
Number of restricted shares issued to former employees         131 2,200    
Class B common stock [Member] | Common Stock [Member]                
Equity (Textual)                
Common stock issued for compensation, Shares             311,000  
Common stock issued for exercises of stock options, Shares         2,000 12,000 3,000  
Common stock issued for deferred stock units, Shares           20,000 9,000  
Retirement of common stock issued to former employees of IDT Corporation, Shares             (3,000)  
Common stock issued or to be issued for compensation, Shares         121,000 265,000    
Class B common stock [Member] | Treasury Stock [Member]                
Equity (Textual)                
Number of shares held in treasury stock value       $ 197,344       $ 348,051
Treasury stock, shares       9,982       35,846
Stock options [Member]                
Equity (Textual)                
Common stock issued for exercises of stock options, Shares         (1,631) (12,053) (3,065)  
Stock options [Member] | Class B common stock [Member]                
Equity (Textual)                
Common stock issued for exercises of stock options, Shares         1,631 12,053 3,065  
Common stock issued for exercises of stock options         $ 9,299 $ 68,341 $ 17,000