Document and Entity Information [Abstract] Statement [Table] Equity Components [Axis] Equity Component [Domain] Common Stock [Member] Class of Stock [Axis] Class of Stock [Domain] Common Class A [Member] Class A common stock Class A common stock [Member] Common Class B [Member] Class B common stock Class B common stock [Member] Statement [Line Items] Entity Registrant Name Entity Central Index Key Amendment Flag Current Fiscal Year End Date Document Type Document Period End Date Document Fiscal Period Focus Document Fiscal Year Focus Entity Filer Category Entity Common Stock, Shares Outstanding Balance Sheets [Abstract] Assets [Abstract] Assets Assets, Current [Abstract] Current Assets: Cash and cash equivalents at beginning of period Cash and cash equivalents Cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Accounts Receivable, Net, Current Trade accounts receivable, net of allowance for doubtful accounts of $4 at October 31, 2013 and July 31, 2013 Other Assets, Current Other current assets Assets, Current Total current assets Prepaid Expense, Noncurrent Prepaid expenses Intangible Assets, Net (Excluding Goodwill) Intangibles Assets Total assets Liabilities and Equity [Abstract] Liabilities and equity Liabilities, Current [Abstract] Current liabilities: Accounts Payable, Trade, Current Trade accounts payable Accrued Liabilities, Current Accrued expenses TOTAL Due to Related Parties, Current Due to IDT Corporation Deferred Revenue, Current Deferred revenue Taxes Payable, Current Income taxes payable Liabilities, Current Total current liabilities Deferred Revenue, Noncurrent Deferred revenue - long-term portion Liabilities TOTAL LIABILITIES Total liabilities Commitments and Contingencies Commitments and contingencies Equity [Abstract] Equity: Stockholders' Equity Attributable to Parent [Abstract] Straight Path Communications stockholders' equity: Preferred Stock, Value, Issued Preferred stock, $.01 par value; authorized shares - 3,000; no shares issued Common Stock, Value, Issued Common stock value Additional Paid in Capital Additional paid-in capital Retained Earnings (Accumulated Deficit) Accumulated deficit Stockholders' Equity Attributable to Parent Total Straight Path Communications stockholders'equity Stockholders' Equity Attributable to Noncontrolling Interest Noncontrolling interests Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total equity Beginning balance Ending Balance Liabilities and Equity Liabilities and equity Total liabilities and equity Beginning balance Ending Balance Allowance for Doubtful Accounts Receivable Net of allowance for doubtful accounts Allowance for doubtful accounts, Balance at beginning of year Allowance for doubtful accounts, Balance at end of year Preferred Stock, Par or Stated Value Per Share Preferred stock, Par value Preferred Stock, Shares Authorized Preferred stock, Shares authorized Preferred Stock, Shares Issued Preferred stock, Shares issued Common Stock, Par or Stated Value Per Share Common stock, Par value Common Stock, Shares Authorized Common stock, Shares authorized Common Stock, Shares, Issued Common stock shares distributed Common stock, Shares issued Common Stock, Shares, Outstanding Common stock shares outstanding Common stock, Shares outstanding Statements of Operations [Abstract] Revenues Revenues Revenues Revenues Included in Direct cost of revenues Costs and Expenses [Abstract] Costs and expenses: Cost of Revenue Included in Direct cost of revenues Direct cost of revenues Selling, General and Administrative Expense Included in Selling, general and administrative expenses Selling, general and administrative Costs and Expenses Total costs and expenses Operating Income (Loss) Loss from operations (LOSS) INCOME FROM OPERATIONS Interest Income, Other Interest income Other Income Income from IDT Corporation payments of liabilities Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Loss before income taxes Income Tax Expense (Benefit) Provision for income taxes PROVISION FOR INCOME TAXES (Provision for) benefit from income taxes Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net loss Net loss Net loss Income (Loss) Attributable to Noncontrolling Interest Net loss attributable to noncontrolling interests Net loss attributable to noncontrolling interests Net Income (Loss) Attributable to Parent Net loss Net (loss) income Net loss attributable to Straight Path Communications Inc. Earnings Per Share, Basic and Diluted Basic and diluted loss per share attributable to Straight Path Communications Inc. stockholders Weighted Average Number of Shares Outstanding, Basic and Diluted Weighted-average number of shares used in calculation of basic and diluted loss per share Statement of Cash Flows [Abstract] Net Cash Provided by (Used in) Operating Activities [Abstract] Operating activities Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net loss to net cash used in operating activities: Provision for Doubtful Accounts Provision for doubtful accounts receivable Share-based Compensation Stock-based compensation Stock-based compensation Increase (Decrease) in Operating Capital [Abstract] Change in assets and liabilities: Increase (Decrease) in Accounts Receivable Trade accounts receivable Trade accounts receivable, net Increase (Decrease) in Prepaid Expense and Other Assets Other current assets and prepaid expenses Other current assets and prepaid expenses, Increase (Decrease) in Accounts Payable and Accrued Liabilities Trade accounts payable and accrued expenses Increase (Decrease) in Due to Related Parties Due to IDT Corporation Increase (Decrease) in Deferred Revenue Deferred revenue Increase (Decrease) in Income Taxes Payable Income taxes payable Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net cash used in operating activities Net Cash Provided by (Used in) Investing Activities [Abstract] Investing activities Proceeds from Sale of Other Assets Cash Received from Exchange of Licenses Proceeds from sale of rights in wireless spectrum Payments to Acquire Intangible Assets Purchase of spectrum licenses Purchase of spectrum licenses Proceeds from Sale and Maturity of Other Investments Proceeds from maturity of certificates of deposit Net Cash Provided by (Used in) Investing Activities, Continuing Operations Net cash (used in) provided by investing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Financing activities Proceeds from (Payments for) Other Financing Activities Funding provided by IDT Corporation, net of repayments Repayments of Notes Payable Repayment of note payable Repayments of note payable Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net cash provided by financing activities Cash and Cash Equivalents, Period Increase (Decrease) Net (decrease) increase in cash and cash equivalents Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental schedule of non-cash investing and financing activities Related Party Transaction, Amounts of Transaction Amount due to IDT Corporation contributed to equity Basis of Presentation [Abstract] Basis of Presentation [Abstract] Business Description and Basis of Presentation [Text Block] Basis of Presentation Fair Value Measurements [Abstract] Fair Value Disclosures [Text Block] Fair Value Measurements Stockholders' Equity Note Disclosure [Text Block] Equity Loss Per Share [Abstract] (Loss) earnings per share attributable to Straight Path Communications Inc. stockholders: Earnings Per Share [Text Block] Loss Per Share Related Party Transactions [Abstract] Related Party Transactions [Abstract] Related Party Transactions Disclosure [Text Block] Related Party Transactions Concentration Of Customers [Abstract] Concentration of Customers [Abstract] Concentration of customers. Concentration Of Customers [Text Block] Concentration of Customers Concentration of customers. Business Segment Information [Abstract] Business Segment Information Segment Reporting Disclosure [Text Block] Business Segment Information Commitments and Contingencies [Abstract] Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Schedule of Stockholders Equity [Table Text Block] Changes in the components of equity Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Shares were excluded from the diluted earnings per share computations Schedule of Related Party Transactions [Table Text Block] Schedule expenses incurred by related party charges Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block] Revenues from transactions with a single customer Schedule of Segment Reporting Information, by Segment [Table Text Block] Summary of operating results for the business segments Summary Of Business Segment Aggregate Assets [Table Text Block] Summary of total assets for the business segments Tabular disclosure of business segment aggregate assets. Schedule of Subsidiary of Limited Liability Company or Limited Partnership [Table] Legal Entity [Axis] Entity [Domain] Subsidiaries [Member] Straight Path Spectrum [Member] Straight Path IP [Member] Straight Path IP [Member] Straight Path IP [Member] Idt [Member] IDT[Member] IDT (Member) Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Patents [Member] Subsidiary of Limited Liability Company or Limited Partnership [Line Items] Description of Business and Summary of Significant Accounting Policies (Textual) [Abstract] Description of Business and Summary of Significant Accounting Policies (Textual) Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions Ownership in Straight Path Spectrum Parent [Member] Equity [Member] Noncontrolling Interest [Member] Noncontrolling Interests Noncontrolling Interests [Member] Equity (Textual) [Abstract] Equity (Textual) Equity (Textual) Related Party Transaction [Axis] Related Party Transaction [Domain] Title of Individual [Axis] Relationship to Entity [Domain] Director [Member] Chief Executive Officer [Member] Chief Financial Officer [Member] Non Employee Director [Member] Non Employee Director. Consultants [Member] consultants. Stock Issued During Period, Shares, Issued for Services Stock issued during period, Shares Stock Issued During Period, Shares, Issued for Services Stock Issued During Period, Value, Issued for Services Aggregate fair value Stock Issued During Period, Value, Issued for Services Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Options exercise price Distribution Ratio Distributed shares Shares disribution. Stock Issued During Period, Shares, Restricted Stock Award, Gross Common stock restricted shares Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights Description of restricted shares vesting condition Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights Share Based Compensation Arrangement By Share Based Payment Award Option To Purchase Number Of Shares At Time Of Spin Off Options to purchase number of shares at time of spin off Options to purchase number of shares at time of spin off. Schedule of Stock by Class [Table] Option Indexed to Issuer's Equity, Type [Axis] Option Indexed to Issuer's Equity, Type [Domain] Employee Stock Option [Member] Stock options [Member] Non Vested Restricted Class B Common Stock [Member] Non-vested restricted Class B common stock [Member] Non-vested restricted Class B common stock. Class of Stock [Line Items] Earnings Per Share, Diluted, Other Disclosures [Abstract] Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Shares excluded from the calculation of diluted loss per share Schedule of Related Party Transactions, by Related Party [Table] Transmission Service Agreement [Member] Transmission Service Agreement [Member] International Discount Telecommunications [Member] IDT [Member] International discount telecommunications. Related Party Transaction [Line Items] Related Party Transaction, Due from (to) Related Party [Abstract] Related Party Transaction, Due from (to) Related Party [Abstract] Payments By Related Party Parent Payments by IDT on behalf of the Company Payments by related party parent. Deferred Taxes Utilized By Related Party Deferred taxes offset against IDT net operating losses Deferred taxes utilized by related party. Cash Repayments To Related Party Net Of Advances Cash repayments, net of advances Cash repayments to related party net of advances. Amount Due To Related Party Contributed To Equity Amount due to IDT contributed to equity Amount due to related party contributed to equity. Average Related Party Transaction Due From To Related Party Average balance during the year Average Related Party transaction due from to pelated party. Related Party Transaction, Expenses from Transactions with Related Party Regulatory fees Included in direct cost of revenues Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party Included in selling, general and administrative expenses Payroll, benefits, insurance, facilities and other expenses Related Party Transactions Textual [Abstract] Income From Payments Of Liabilities Income from payments of liabilities. Customer [Axis] Customer [Domain] Covad Communications Group [Member] Covad Communications Group [Member] Covad Communications Group. American Telephone And Telegraph [Member] AT&T[Member] American Telephone And Telegraph. Verizon [Member] Verizon [Member] Verizon. Airband Communications [Member] Airband Communications [Member] Airband Communications. Schedule of Segment Reporting Information, by Segment [Table] Segment Reporting Information [Line Items] Segment Reporting Information, Profit (Loss) [Abstract] Summary of operating results for the business segments Segment Reporting Information, Additional Information [Abstract] Summary of total assets for the business segments Number of Reportable Segments Reportable Segments Product Liability Contingency [Table] Geographical [Axis] Geographical [Domain] NEW YORK Economic Area License [Member] 39 GHz Economic Area [Member] Economic area license. Rectangular Service Area License [Member] 39 GHz Rectangular Service Area [Member] Rectangular service area license. Local Multipoint Distribution Service License [Member] LMDS 28 GHz range [Member] Local multipoint distribution service license. Former Chief Executive Officer [Member] Former Chief Executive Officer [Member] Former Chief Executive Officer [Member] Range [Axis] Range [Domain]