v3.26.1
Document And Entity Information - shares
 9 Months Ended
Apr. 30, 2026
Jun. 01, 2026
Document Information [Line Items]    
Entity Central Index Key 0001005731  
Entity Registrant Name IDT CORP  
Amendment Flag false  
Current Fiscal Year End Date --07-31  
Document Fiscal Period Focus Q3  
Document Fiscal Year Focus 2026  
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Apr. 30, 2026  
Document Transition Report false  
Entity File Number 1-16371  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 22-3415036  
Entity Address, Address Line One 520 Broad Street  
Entity Address, City or Town Newark  
Entity Address, State or Province NJ  
Entity Address, Postal Zip Code 07102  
City Area Code 973  
Local Phone Number 438-1000  
Title of 12(b) Security Class B common stock, par value $.01 per share  
Security Exchange Name NYSE  
Trading Symbol IDT  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Common Class B [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   23,294,240
Common Class A [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   1,574,326