IDT Financial Services Holding Limited Assets and Liabilities Held for Sale (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jul. 31, 2017
Current assets held for sale:
Cash and cash equivalents	$ 6,833	$ 5,716
Total current assets held for sale	147,429	124,267
Noncurrent assets held for sale:
Other assets	5,765	5,134
Current liabilities held for sale:
Total current liabilities held for sale	138,324	115,318
Noncurrent liabilities held for sale:
Total noncurrent liabilities held for sale	570	550
IDT Financial Services Holding Limited [Member]
Current assets held for sale:
Cash and cash equivalents	6,833	5,716
Restricted cash and cash equivalents	137,703	115,609
Trade accounts receivable, net of allowance for doubtful accounts of $3,631 and $2,550 at April 30, 2018 and July 31, 2017, respectively	1,591	1,844
Prepaid expenses	770	758
Other current assets	532	340
Total current assets held for sale	147,429	124,267
Noncurrent assets held for sale:
Property, plant and equipment, net	15	24
Other intangibles, net	153	165
Other assets	5,597	4,945
Total noncurrent assets held for sale	5,765	5,134
Current liabilities held for sale:
Trade accounts payable	1,049	372
Accrued expenses	205	226
Customer deposits	137,055	114,689
Other current liabilities	15	31
Total current liabilities held for sale	138,324	115,318
Noncurrent liabilities held for sale:
Other liabilities	570	550
Total noncurrent liabilities held for sale	$ 570	$ 550