Document and Entity Information - shares	6 Months Ended
	Jan. 31, 2019	Mar. 07, 2019
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-Q
Document Period End Date	Jan. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Ex Transition Period	false
Class A common stock
Entity Common Stock Shares Outstanding		1,574,326
Class B common stock
Entity Common Stock Shares Outstanding		24,708,627