Document and Entity Information - shares	6 Months Ended
	Jan. 31, 2020	Mar. 06, 2020
Entity Registrant Name	IDT CORP
Entity Central Index Key	0001005731
Amendment Flag	false
Current Fiscal Year End Date	--07-31
Document Type	10-Q
Document Period End Date	Jan. 31, 2020
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2020
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity File Number	1-16371
Entity Interactive Data Current	Yes
Entity Incorporation State Country Code	DE
Class A common stock
Entity Common Stock Shares Outstanding		1,574,326
Class B common stock
Entity Common Stock Shares Outstanding		25,015,600