Line of credit facility (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
	Apr. 30, 2013	Mar. 31, 2013	Jul. 31, 2012	Jul. 30, 2012
Line of Credit Facility (Textual)
Maximum principal amount can be borrowed				$ 25.0
Amount of additional borrowing	8.0
Interest Rate Description			Interest per annum, at the option of IDT Telecom, at either (a) the U.S. Prime Rate less 125 basis points, or (b) the LIBOR rate adjusted by the Regulation D maximum reserve requirement plus 150 basis points and is payable monthly.
Interest rate		1.7037%
Maturity date			Jul. 11, 2014
Unused commitment fee per annum			0.375%
Line of Credit Facility, Covenant Compliance			IDT Telecom is required to comply with various affirmative and negative covenants as well as maintain certain financial targets and ratios during the term of the line of credit, including IDT Telecom may not pay any dividend on its capital stock and IDT Telecom's aggregate loans and advances to affiliates or subsidiaries may not exceed $70.0 million.
Amount repaid	8
Aggregate loans and advances outstanding to affiliates and subsidiaries	$ 54.5