XML 16 R1.htm IDEA: XBRL DOCUMENT v3.10.0.1
Document and Entity Information - USD ($)
$ in Millions
 12 Months Ended
Jul. 31, 2018
Oct. 09, 2018
Jan. 31, 2018
Entity Registrant Name IDT CORP    
Entity Central Index Key 0001005731    
Amendment Flag false    
Trading Symbol IDT    
Current Fiscal Year End Date --07-31    
Document Type 10-K    
Document Period End Date Jul. 31, 2018    
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 220.2
Class A Common Stock      
Entity Common Stock Shares Outstanding   1,574,326  
Class B Common Stock      
Entity Common Stock Shares Outstanding   22,143,898