Document and Entity Information [Abstract] Statement [Table] 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 Trading Symbol Document Period End Date Document Fiscal Period Focus Document Fiscal Year Focus Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Entity Public Float Entity Common Stock, Shares Outstanding Balance Sheets [Abstract] Common Stock To Be Issued [Member] Common Stock To Be Issued Common stock to be issued. Assets [Abstract] Assets Assets, Current [Abstract] Current assets: Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Cash and cash equivalents Cash and cash equivalents at beginning of year Cash and cash equivalents at end of year Accounts Receivable, Net, Current Trade accounts receivable, net of allowance for doubtful accounts of $19 and $0, respectively Inventory, Net Inventory Assets Held For Sale Intellectual Property Business Assets held for sale - Intellectual Property Business Assets held for sale intellectual property business. Prepaid Expense and Other Assets, Current TOTAL PREPAID EXPENSES AND OTHER CURRENT ASSETS Prepaid expenses and other current assets Assets, Current Total current assets Prepaid Expenses Related To Sale Of Ip Business To Idt Prepaid expenses - related to the sale of IP Business to IDT Prepaid expenses related to the sale of ip business to idt. Intangible Assets, Net (Excluding Goodwill) Intangible assets Other Assets, Noncurrent Other assets Assets Total assets Total assets Liabilities and Equity [Abstract] Liabilities and Equity Liabilities, Current [Abstract] Current liabilities: Accounts Payable, Trade, Current Trade accounts payable (related party of $29 and $25) Accrued Liabilities, Current Accrued expenses (related party of $900 and $65) Accrued expenses TOTAL ACCRUED EXPENSES Liabilities Held For Sale Intellectual Property Business Liabilities held for sale - Intellectual Property Business Liabilities held for sale intellectual property business . Fcc Consent Decree Payable Amount of liabilities Fcc consent decree payable. Loans Payable Loans payable, net of debt discount of $1,101 and $0, respectively Loans payable Deferred Revenue, Current Deferred revenue Taxes Payable, Current Income taxes payable Liabilities, Current Total current liabilities Estimated Litigation Liability, Noncurrent Settlement of litigation Deferred Revenue, Noncurrent Deferred revenue - long-term portion Liabilities TOTAL LIABILITIES Total liabilities Commitments and Contingencies Commitments and contingencies Equity [Abstract] Equity (Deficiency) Equity Stockholders' Equity Attributable to Parent [Abstract] Straight Path Communications Inc. stockholders' equity: Preferred Stock, Value, Issued Preferred stock, $0.01 par value; 3,000 shares authorized; no shares issued and outstanding Common Stock, Value, Issued Common stock value Additional Paid in Capital Additional paid-in capital Retained Earnings (Accumulated Deficit) (Accumulated deficit) retained earnings Accumulated deficit Retained earnings Treasury Stock, Value Treasury stock, 40 shares at cost at July 31, 2017 and 2016 Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total Straight Path Communications Inc. stockholders' equity (deficiency) Balance Balance Stockholders' Equity Attributable to Noncontrolling Interest Noncontrolling interests Noncontrolling interests Stockholders' Equity Attributable to Parent Total Straight Path Communications Inc. stockholders' equity Total equity (deficiency) Balance Balance Liabilities and Equity Total liabilities and equity (deficiency) Equity Components [Axis] Equity Component [Domain] Common Stock [Member] Common Stock [Member] Common Stock 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 Accounts Payable, Related Parties, Current Trade accounts payable related party Accrued Expenses Related Parties Current Accrued expenses related party Amount for accounts payable to related parties. Debt Instrument, Unamortized Discount, Current Loans payable, net of debt discount 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 Preferred Stock, Shares Outstanding Preferred stock, shares outstanding 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 Treasury Stock, Shares Treasury stock, shares Treasury stock, shares Statements of Operations [Abstract] Revenues Revenues Revenues Revenues Costs and Expenses [Abstract] Costs and expenses: Cost of Revenue Direct cost of revenues Research and Development Expense Research and development Research and development Research and development expenses Selling, General and Administrative Expense Selling, general and administrative expense Selling, general and administrative (related party of $1,613, $596 and $420) Selling, general and administrative Costs and Expenses Total costs and expenses Income Loss From Operations Before Extraordinary Items (Loss) income from operations before items listed below Income loss from operations before extraordinary items. Income (loss) from operations before items listed below Civil Penalty Fcc Decree Civil penalty - FCC consent decree Civil penalty - FCC consent decree A civil penalty or civil fine is a financial penalty imposed by a government agency as restitution for wrongdoing. Civil penalty - FCC consent decree Civil penalty - FCC consent decree Litigation Settlement, Expense Settlement of litigation Legal expense Settlement of initial payment Stockholder settlement Settlement of litigation Settlement of litigation Operating Income (Loss) Income (loss) from operations Income (loss) from operations Income (loss) from operations Other Income and Expenses [Abstract] Other income (expense): Interest Expense Debt Including Amortization Interest expense, including amortization of debt discounts Interest expense Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, including amortization of debt discount (premium) and financing costs. Interest expense, including amortization of debt discounts Interest expense Interest Income, Other Interest income Other Income Income from IDT Corporation payments of liabilities Other income Income from IDT Corporation payments of liabilities Other Nonoperating Income (Expense) Other income Total other income (expense) Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income (loss) before income taxes Income Tax Expense (Benefit) Income tax expense (benefit) BENEFIT FROM (PROVISION FOR) INCOME TAXES PROVISION FOR (INCOME TAXES) INCOME TAX BENEFITS INCOME TAX BENEFITS (PROVISION FOR INCOME TAXES) Provision for income tax benefits (income taxes) BENEFIT FROM (PROVISION FOR) INCOME TAXES Income tax benefits provision for income taxes Income tax benefits (provision for income taxes) Income tax benefits (provision for income taxes) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net (loss) income Net (loss) income Net loss Net loss Net loss Income (Loss) Attributable to Noncontrolling Interest Net loss (income) attributable to noncontrolling interests Net loss attributable to noncontrolling interests 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 SPCI Net loss attributable to Straight Path Communications Inc. Net (loss) income attributable to SPCI Earnings Per Share [Abstract] Loss per share attributable to Straight Path Communications Inc. stockholders: Earnings Per Share, Basic and Diluted Basic and diluted Loss per share - basic and diluted Weighted Average Number of Shares Outstanding, Diluted [Abstract] Weighted-average number of shares used in calculation of loss per share: Weighted Average Number of Shares Outstanding, Basic and Diluted Basic and diluted Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party Selling, general and administrative related party Statements of Equity (Deficit) [Abstract] Additional Paid-in Capital [Member] Additional Paid-In Capital Additional Paid-In Capital [Member] Retained Earnings [Member] (Accumulated Deficit) Retained Earnings Treasury Stock [Member] Treasury Stock Treasury Stock [Member] Noncontrolling Interest [Member] Noncontrolling Interests Noncontrolling Interests [Member] Shares, Outstanding Balance, shares Balance, shares Common Stock Issued Or To Be Issued For Compensation Common stock issued or to be issued for compensation Common stock issued or to be issued for compensation. Common Stock Issued Or To Be Issued For Compensation Shares Common stock issued or to be issued for compensation, shares Common stock issued or to be issued for compensation shares. Stock Issued During Period, Value, Share-based Compensation, Gross Common stock issued for compensation Common stock issued or to be issued for compensation Stock Issued During Period, Shares, Share-based Compensation, Gross Common stock issued for compensation, shares Stock Issued During Period, Value, Stock Options Exercised Common stock issued for exercises of stock options, value Common stock issued for exercises of stock options Common stock issued upon exercise of stock options Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Common stock issued for exercises of stock options, shares Stock options, Exercised Stock Issued During Period, Value, Other Common stock issued for deferred stock units Stock Issued During Period, Shares, Other Common stock issued for deferred stock units, shares Reversal Of Prior Period Related Party Payables Reversal of prior period related party payables Reversal of prior period related party payables. Stock Issued During Period, Value, Employee Benefit Plan Retirement of common stock issued to former employees of IDT Corporation Stock Issued During Period, Shares, Employee Benefit Plan Retirement of common stock issued to former employees of IDT Corporation, shares Common Stock With Held For Tax Purposes Common stock repurchased for withholding tax purposes Common stock repurchased for withholding tax purposes Common stock withheld for tax purposes. Common stock repurchased for withholding tax purposes Share-based Compensation Stock options issued for compensation Stock-based compensation Stock Issued During Period, Value, Treasury Stock Reissued Sale of treasury stock Sale of treasury stock / Issuance of treasury shares for 401K match Stock Issued During Period, Value, Restricted Stock Award, Forfeitures Forfeiture of unvested shares Stock Issued During Period, Shares, Share-based Compensation, Forfeited Forfeiture of unvested shares, shares Stock Issued During Period Issuance Of Warrants With Loans Payable Issuance of warrants with loans payable Issuance of warrants with loans payable. Stock Issued During Period Issuance Of Warrants With Loans Payable Shares Issuance of warrants with loans payable, shares Issuance of warrants with loans payable shares. Stock Issued During Period Common Stock Issued For Exercises Of Warrants Common stock issued for exercises of warrants Common stock issued for exercises of warrants. Stock Issued During Period Common Stock Issued For Exercises Of Warrants Shares Common stock issued for exercises of warrants, shares Common stock issued for exercises of warrants shares. Stock Issued During Period, Value, Stock Dividend Dividends Statement of Cash Flows [Abstract] Net Cash Provided by (Used in) Operating Activities, Continuing Operations [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: Allocated Share-based Compensation Expense Common stock issued or to be issued for compensation Common stock issued or to be issued for compensation Amortization of Debt Discount (Premium) Amortization of debt discounts Provision for Doubtful Accounts Allowance for doubtful accounts Issuance Of Treasury Shares Issuance of treasury shares for 401K match Treasury stock may have come from a repurchase or buyback from shareholders, or it may have never been issued to the public in the first place. Gain (Loss) on Sale of Properties Gain from sale of patent Gain from sale of patent Deferred Income Tax Expense (Benefit) Deferred income taxes Total Increase (Decrease) in Operating Capital [Abstract] Changes in assets and liabilities: Increase (Decrease) in Accounts Receivable Trade accounts receivable Trade accounts receivable Increase (Decrease) in Inventories Inventory Inventory Increase Decrease In Assets Held For Sale Intellectual Property Business Assets held for sale - Intellectual Property Business Increase decrease in assets held for sale intellectual property business. Increase (Decrease) in Prepaid Expenses, Other Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense Prepaid expenses - settlements Prepaid expenses - related to settlements and licensing Increase (Decrease) in Other Operating Assets Other assets Increase (Decrease) in Accounts Payable, Trade Trade accounts payable Increase (Decrease) in Accrued Liabilities Accrued expenses Increase Decrease In Liabilities Held For Sale Intellectual Property Business Liabilities held for sale - Intellectual Property Business Increase decrease in liabilities held for sale intellectual property business Increase Decrease Fcc Consent Decree Payable FCC consent decree payable The increase (decrease) in obligations consent decree payable. 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 Increase Decrease In Settlement Of Litigation Settlement of litigation Settlement of litigation. Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net cash used in operating activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Investing activities: Payments Of Prepaid Expenses Related To Sale Of Ip Business To Idt Prepaid expenses - related to sale of IP business to IDT Payments of prepaid expenses related to sale of IP business to IDT. Payments to Acquire Intangible Assets Purchase of spectrum licenses Purchase of intangibles Proceeds from Sale of Intangible Assets Proceeds from sale of patent Net Cash Provided by (Used in) Investing Activities, Continuing Operations Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Financing activities: Proceeds from Loans Proceeds from loans payable Costs Related To Loans Payable Costs related to loans payable Costs related to loans payable Payments Of Stock Issuance Exercise Stock Option Value of payments of stock issuance exercise stock option. Common stock issued upon exercise of stock options Proceeds from Sale of Treasury Stock Sale of treasury stock Payments of Dividends Dividends paid to stockholders of noncontrolling interests Dividends paid to stockholders of noncontrolling interests Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net cash provided by (used in) financing activities Cash and Cash Equivalents, Period Increase (Decrease) Net decrease in cash and cash equivalents Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental schedule of noncash activities Non Cash Reclassification Of Prepaid Marketing To Inventory Reclassification of prepaid marketing to inventory The amount of non cash reclassification of prepaid marketing to inventory. Exercises Of Warrants Reducing Loans Payable Exercises of warrants reducing loans payable Exercises of warrants reducing loans payable. Noncash Reversal Of Prior Period Related Party Payables Reversal of prior period related party payables Noncash reversal of prior period related party payables. Supplemental Cash Flow Information [Abstract] Supplemental cash flow information Interest Paid, Net Cash paid during the year for interest Income Taxes Paid Cash paid during the year for income taxes Description of Business and Summary of Significant Accounting Policies [Abstract] Business Description and Accounting Policies [Text Block] Description of Business and Summary of Significant Accounting Policies Verizon Merger Agreement [Abstract] Verizon Merger Agreement [Text Block] Verizon Merger Agreement The entire disclosure Verizon Merger Agreement. Settlement of Claims with IDT and Sale of Straight Path IP Group [Abstract] Settlement of Claims with IDT and Sale of Straight Path IP Group [Abstract] Settlement Of Claims With Idt And Sale Of Straight Path Ip Group [Text Block] Settlement of Claims with IDT and Sale of Straight Path IP Group The entire disclosure of settlement of claims. Fair Value Measurements [Abstract] Fair Value Disclosures [Text Block] Fair Value Measurements Income Taxes [Abstract] Income Taxes Income Taxes Prepaid Expenses and Other Current Assets [Abstract] Prepaid Expenses And Other Current Assets [Text Block] Prepaid Expenses and Other Current Assets The entire disclosure for prepaid expenses and other current assets. Accrued Expenses [Abstract] Accounts Payable and Accrued Liabilities Disclosure [Text Block] Accrued Expenses Loan Payable [Abstract] Debt Disclosure [Text Block] Loan Payable Stockholders' Equity Note Disclosure [Text Block] Equity Stock-Based Compensation [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Stock-Based Compensation Commitments and Contingencies [Abstract]