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 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] 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 $0 and $0, respectively Prepaid Expense, Current Prepaid expenses - related to settlements and licensing Deferred tax assets Deferred tax assets Other Assets, Current Other current assets Assets, Current Total current assets Prepaid Expense, Noncurrent Prepaid expenses - related to settlements and licensing - long-term portion Intangible Assets, Net (Excluding Goodwill) Intangible assets Deferred Tax Assets, Net, Noncurrent Deferred tax 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 Accrued Liabilities, Current Accrued expenses TOTAL ACCRUED EXPENSES 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 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) Retained earnings Retained earnings Treasury Stock, Value Treasury stock, 42 shares at cost Treasury stock, 42 shares at cost Stockholders' Equity Attributable to Parent Total Straight Path Communications Inc. stockholders' equity Total Straight Path Communications Inc. stockholders' equity Stockholders' Equity Attributable to Noncontrolling Interest Noncontrolling interests Noncontrolling interests Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total equity Balance Beginning Balance Liabilities and Equity Total liabilities and equity 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 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 Statements of Operations [Abstract] Revenues Revenues Revenues Revenues Costs and Expenses [Abstract] Costs and expenses: Cost of Revenue Direct cost of revenues Selling, General and Administrative Expense Selling, general and administrative Costs and Expenses Total costs and expenses Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Income (loss) from operations before items listed below Income (loss) from operations before items listed below Gain (Loss) on Disposition of Other Assets Gain on sale of rights in wireless spectrum included in loss from operations Gain on settlement of rights in wireless spectrum Gain on Exchange of Licenses Gain (Loss) Related to Litigation Settlement Loss on settlement of Straight Path Spectrum legal proceedings included in loss from operations Loss on settlement of Straight Path Spectrum legal proceedings Operating Income (Loss) Income (loss) from operations Loss from operations Loss from operations Other Income and Expenses [Abstract] Other income: Interest Income, Other Interest income Other Income Income from IDT Corporation payments of liabilities Other income Income from IDT Corporation payments of liabilities Income From Payments Of Liabilities Income from IDT Corporation payments of liabilities Income from payments of liabilities. Interest and Other Income Other income Total other income Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Income (loss) before income taxes Income Tax Expense (Benefit) Income tax expense (benefit) (PROVISION FOR) BENEFIT FROM INCOME TAXES Provision for (income taxes) income tax benefits Provision for (income taxes) income tax benefits Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net loss Net (loss) income Net (loss) income Income (Loss) Attributable to Noncontrolling Interest Net loss (income) attributable to noncontrolling interests Net loss attributable to noncontrolling interests Net loss (income) attributable to noncontrolling interests Net Income (Loss) Attributable to Parent Net loss Net (loss) income Net (loss) income attributable to Straight Path Communications Inc. Net (loss) income attributable to SPCI Earnings Per Share [Abstract] Earnings (loss) per share attributable to Straight Path Communications Inc. stockholders: Earnings Per Share, Basic Income (loss) per share - basic Basic Earnings Per Share, Diluted Income (loss) per share - diluted Diluted Weighted Average Number of Shares Outstanding, Diluted [Abstract] Weighted-average number of shares used in calculation of earnings (loss) per share: Weighted Average Number of Shares Outstanding, Basic Basic weighted-average number of shares Basic Weighted Average Number of Shares Outstanding, Diluted Diluted weighted-average number of shares Diluted Statements of Equity (Deficit) [Abstract] Group Equity [Member] Group Equity Group Equity [Member] Group Equity. Common Stock To Be Issued [Member] Common Stock To Be Issued Common stock to be issued. Additional Paid-in Capital [Member] Additional paid-in capital Additional Paid-In Capital [Member] Retained Earnings [Member] Retained Earnings Treasury Stock [Member] Treasury Stock Noncontrolling Interest [Member] Noncontrolling interests Noncontrolling Interests [Member] Shares, Outstanding Balance Beginning, Shares Balance, Shares Related Party Transaction, Amounts of Transaction Amount due to IDT Corporation contributed to equity Capital Contribution From Parent Capital contribution from IDT Corporation in connection with the Spin-Off Capital contributed by parent. Stockholders' Equity Note, Spinoff Transaction Incorporation of Company and share distribution on Spin-Off Stockholders Equity Note Spinoff Transaction Shares Incorporation of Company and share distribution on Spin-Off, Shares The change in equity as a result of a spin-off transaction (a regular or reverse spin-off) which is based on the recorded amounts, 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 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, Stock Options Exercised Common stock issued for exercises of stock options 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 exercises of deferred stock units Stock Issued During Period, Shares, Other Common stock issued for exercises of deferred stock units, Shares 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 Reversal Of Prior Period Related Party Payables Reversal of prior period related party payables Reversal of prior period related party payables. 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 Stock Issued During Period, Value, Treasury Stock Reissued Sale of treasury stock 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 Share-based Compensation Stock-based compensation Stock-based compensation Stock Issued During Period, Value, Stock Dividend Dividends 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) income to net cash (used in) provided by 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 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, net Increase (Decrease) in Prepaid Expense Prepaid expenses - settlements Prepaid expenses - related to settlements and licensing Increase (Decrease) in Other Current Assets Other current assets Other current assets Increase (Decrease) in Prepaid Expense and Other Assets Other current assets and prepaid expenses Other assets Increase (Decrease) in Accounts Payable, Trade Trade accounts payable Increase (Decrease) in Accrued Liabilities 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) provided by operating activities Net Cash Provided by (Used in) Investing Activities [Abstract] Investing activities: 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 [Abstract] Financing activities: Proceeds from Sale of Treasury Stock Sale of treasury stock Stock Issued, Value, Stock Options Exercised, Net of Tax Benefit (Expense) Common stock issued upon exercise of stock options Common stock issued upon exercise of stock options Payments of Dividends Dividends paid to stockholders of noncontrolling interests Dividends paid to stockholders of noncontrolling interests Proceeds from (Payments for) Other Financing Activities Funding provided by IDT Corporation, net of repayments Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net cash (used in) 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 noncash activities 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 Income Taxes Paid, Net 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 Fair Value Measurements [Abstract] Fair Value Disclosures [Text Block] Fair Value Measurements Income Taxes [Abstract] Income Taxes Accrued Expenses [Abstract] Accounts Payable and Accrued Liabilities Disclosure [Text Block] Accrued Expenses 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] Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Related Party Transactions [Abstract] Related Party Transactions [Abstract] Related Party Transactions Disclosure [Text Block] Related Party Transactions Revenues In Wireless Spectrum [Abstract] Revenues and Gain on Sale of Rights in Wireless Spectrum [Abstract] Revenues in wireless spectrum. Revenues In Wireless Spectrum Disclosure [Text Block] Revenues in Wireless Spectrum Revenues in wireless spectrum Disclosure. Business Segment Information [Abstract] Business Segment Information Segment Reporting Disclosure [Text Block] Business Segment Information Quarterly Financial Data (Unaudited) [Abstract] Quarterly Financial Information [Text Block] Quarterly Financial Data (Unaudited) Subsequent Events [Abstract] Subsequent Events [Text Block] Subsequent Events Basis of Accounting, Policy [Policy Text Block] Basis of Accounting Use of Estimates, Policy [Policy Text Block] Use of Estimates Revenue Recognition, Policy [Policy Text Block] Revenue Recognition Cost of Sales, Policy [Policy Text Block] Direct Cost of Revenues Cash and Cash Equivalents, Policy [Policy Text Block] Cash Equivalents and Concentrations of Credit Risk Goodwill and Intangible Assets, Policy [Policy Text Block] Intangible Assets Income Tax, Policy [Policy Text Block] Income Taxes Commitments and Contingencies, Policy [Policy Text Block] Contingencies Earnings Per Share, Policy [Policy Text Block] Earnings Per Share Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Stock-Based Compensation Fair Value Measurement, Policy [Policy Text Block] Fair Value Measurements Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block] Allowance for Doubtful Accounts New Accounting Pronouncements, Policy [Policy Text Block] Recently Issued Accounting Pronouncements Subsequent Events, Policy [Policy Text Block] Subsequent Events Schedule of Weighted Average Number of Shares [Table Text Block] Schedule of weighted-average number of shares used in the calculation of basic and diluted earnings per share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Summary of shares excluded from the diluted earnings per share computations Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Schedule of change in the allowance for doubtful accounts Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Summary of (provision for) benefit from income taxes Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Summary of deferred income tax assets Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of differences between income taxes expected at the federal statutory income tax rate and income taxes Summary of Valuation Allowance [Table Text Block] Schedule of change in the valuation allowance for deferred income taxes Schedule of Accrued Liabilities [Table Text Block] Summary of accrued expenses Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Schedule of share based compensation stock option activity Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of future minimum rental commitments of non-cancelable operating leases Schedule Of Change In Liability To Related Party [Table Text Block] Schedule of change in liability to related party Schedule of change in liability to related party. Revenue from External Customers by Products and Services [Table Text Block] Summary of revenues Schedule of Segment Reporting Information, by Segment [Table Text Block] Summary of operating results for the business segments Reconciliation of Assets from Segment to Consolidated [Table Text Block] Summary of total assets for the business segments Schedule of Quarterly Financial Information [Table Text Block] Schedule of quarterly financial data Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Effect of dilutive securities: Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants Stock options Incremental Common Shares Attributable to Dilutive Effect of Nonvested Shares with Forfeitable Dividends Non-vested restricted Class B common stock 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] Stock Option [Member] Non Vested Restricted Classb 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 calculations of diluted earnings (loss) per share Shares excluded from the calculations of diluted earnings (loss) per share Allowance for Doubtful Accounts Receivable [Roll Forward] Reserves deducted from accounts receivable: Schedule of change in the allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Period Increase (Decrease) Allowance for doubtful accounts, Additional changed to cost and expenses Allowance for Doubtful Accounts Receivable, Write-offs Allowance for doubtful accounts, Deductions 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 Group [Member] Straight Path IP [Member] Idt [Member] IDT[Member] IDT 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 Finite-Lived Intangible Assets, Cost Incurred to Renew or Extend Renewal of 39 GHz FCC licenses License renewal costs License Patent Expiration Date License patent expiration date Date which license is set to establish a new expiration date must be form in CCYY-MM-DD format. License Description Description of License Description of the license disclosures. Prior Period Reclassification Adjustment License renewal costs Amount Recovered From Patent Infringers Paid To Law Firm Terms Settlement of litigation, description Amount recovered from patent infringers paid to law firms terms. Income Tax Expense (Benefit), Continuing Operations [Abstract] Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Current: Current Federal Tax Expense (Benefit) Federal Current State and Local Tax Expense (Benefit) State and local Current Income Tax Expense (Benefit) Total Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Deferred: Deferred Federal Income Tax Expense (Benefit) Federal Deferred State and Local Income Tax Expense (Benefit) State and local Deferred Tax Assets, Net [Abstract] Summary of deferred income tax assets Deferred Tax Assets, Gross [Abstract] Deferred income tax assets: Deferred Tax Assets Current [Abstract] Current: Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Accrued expenses Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Stock based compensation Deferred Tax Assets, Deferred Income Deferred revenue on litigation settlements Deferred Tax Assets, Valuation Allowance, Current Valuation allowance Deferred Tax Assets, Net of Valuation Allowance TOTAL CURRENT DEFERRED INCOME TAX ASSETS Deferred Tax Assets Non Current [Abstract] Non-Current: Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Legal Settlements Deferred revenue on litigation settlements Deferred Tax Assets Stock Based Compensation Non Current Stock based compensation Deferred tax assets share-based compensation non current. Deferred Tax Assets, Operating Loss Carryforwards Net operating loss carryforward Deferred Tax Assets, Valuation Allowance, Noncurrent Valuation allowance Valuation allowance Deferred Tax Assets Non Current TOTAL NON-CURRENT DEFERRED INCOME TAX ASSETS Deferred Tax Assets Non Current. Effective Income Tax Rate Reconciliation, Amount [Abstract] Schedule of differences between income taxes expected at the federal statutory income tax rate and income taxes provided Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Federal income tax at statutory rate Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Permanent differences Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Valuation allowance Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount State and local income tax, net of federal benefit Valuation Allowance [Abstract] Reserves deducted from deferred income taxes, net: Deferred Tax Assets, Valuation Allowance Valuation allowance, Beginning balance Valuation allowance, Ending balance Valuation allowance Valuation Allowances and Reserves, Charged to Cost and Expense Valuation allowance, Additions charged to costs and expenses Valuation Allowances and Reserves, Deductions Valuation allowance, Deductions Operating Loss Carryforwards [Table] Winstar Holdings Llc [Member] Winstar Holdings, LLC [Member] Winstar Holdings, LLC [Member] Operating Loss Carryforwards [Line Items] Income Tax (Textual) [Abstract] Income Tax (Textual) Income Tax (Textual) [Abstract] Operating Loss Carryforwards Operating loss carryforwards Operating Loss Carryforwards Expiration Term Operating loss carryforwards expiration term Operating loss carryforwards expiration term. Suspended Losses Offset Taxable Income Suspended losses became available to offset taxable income Suspended losses offset taxable income. Deferred Income Tax Assets Valuation Allowance Percentage Deferred income tax assets valuation allowance percentage Deferred income tax assets valuation allowance. Accrued Liabilities, Current [Abstract] Accrued Expenses [Abstract] Summary of accrued expenses Employee-related Liabilities, Current Accrued compensation Accrued Professional Fees, Current Accrued professional fees Accrued Income Taxes, Current Accrued taxes Income taxes payable Other Accrued Liabilities, Current Other Related Party Transaction [Axis] Related Party Transaction [Domain] Title of Individual [Axis] Relationship to Entity [Domain] Chief Executive Officer And President [Member] Davidi Jonas [Member] Officer [Member] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Equity (Textual) [Abstract] Equity (Textual) Common Stock, Voting Rights Common stock, voting rights Distribution Of Earnings To Stockholders Description Description of distribution of earnings to stockholders Distribution of earnings to stockholders. Stock Issued During Period, Shares, Restricted Stock Award, Forfeited Number of restricted shares issued to former employees Dividends Dividend declared Payments to Noncontrolling Interests Amount paid to minority shareholders Dividends Payable Unpaid dividends Treasury Stock, Number of Shares Held Number of shares held in treasury stock. shares Treasury Stock Repurchased Value Number of shares held in treasury stock. value Amount of treasury stock repurchased value. Option Indexed to Issuer's Equity [Table] Option Indexed to Issuer's Equity [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Stock Options Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Stock options outstanding, Beginning balance Stock options outstanding, Ending balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Stock options, Granted Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Stock options, Exercised ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross. Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Stock options, Cancelled/Forfeited Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Stock options, Vested and expected to vest Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options Stock options, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Weighted- average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Weighted- average Exercise Price outstanding, Beginning balance Weighted- average exercise price outstanding, Beginning balance Weighted- average exercise price outstanding, Ending balance Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Weighted- average exercise price outstanding, Granted Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Weighted- average exercise price outstanding, Exercised Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Weighted- average exercise price outstanding, Cancelled/Forfeited Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Weighted- average exercise price outstanding, Vested and expected to vest Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Weighted- average exercise price outstanding, Exercisable Share Based Compensation Arrangement By Share Based Payment Award Option Weighted Average Remaining Contractual Term Rollforward [Abstract] Weighted- average Remaining Contractual Term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Weighted- average remaining contractual term, Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Weighted- average remaining contractual term, Vested and expected to vest Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Weighted- average remaining contractual term, Exercisable Share Based Compensation Arrangement By Share Based Payment Award Option Aggregate Intrinsic Value Rollforward [Abstract] Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate intrinsic value, Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Aggregate intrinsic value, Vested and expected to vest Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Aggregate intrinsic value, Exercisable Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Chief Financial Officer And Treasurer [Member] Jonathan Rand [Member] Non Employee Director [Member] Person serving on the board of non employee directors (who collectively have responsibility for providing service to the entity). Two Employees [Member] A person employed for wages or salary, especially at non-executive level. One Employee [Member] A person employed for wages or salary, especially at non-executive level. Former Ceo [Member] Former CEO [Member] Highest ranking executive officer, who has ultimate managerial responsibility for the entity and who reports to the board of directors. In addition, the chief executive officer (CEO) may also be the chairman of the board or president. Chief Technology Officer [Member] Jerry Pi [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Stock Based Compensation (Textual) [Abstract] Stock-Based Compensation (Textual) Common Stock, Capital Shares Reserved for Future Issuance Common stock shares reserved Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Common stock available for grant of awards by an additional shares Share Based Compensation Arrangement By Share Based Payment Award Options To Purchase Number Of Shares At Time Of Spin Off Common stock options purchase Number of option outstanding to purchase shares at the time of spin off. Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Options To Purchase Number Of Shares At Time Of Spin Off Issued In Spin Off Common stock shares outstanding option, percentage Percentage of common stock option outstanding to purchase number of shares at the time of spin-off Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price Exercise option price per share Number Of Directors Number of directors Number of directors. Stock Issued During Period, Shares, Issued for Services Number of share granted for service Stock Issued During Period, Value, Issued for Services Common stock with aggregate fair value 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 Restricted common stock shares description Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Aggregate Grant Date Fair Value Estimated value of grant option Srtaight Path IP Share based compensation arrangement by share based payment award options grants in period aggregate grant date fair value. Outstanding common stock of Straight Path IP Percentage Outstanding common stock of Straight Path IP Percentage Stock option purchase of consultant, percentage Option to purchase percentage of outstanding shares percentage during the peroid. Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Consultant stock option vested percentage Grant Of Percentage Of Equity Percentage Board of Directors approved a grant of equity percentage Percentage of equity granted. Share Based Compensation Shares Authorized Under Stock Option Plans Aggregate Exercise Price Grant options equity outstanding of Srtaight Path IP Share based compensation shares authorized under stock option plans aggregate exercise price. Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Discount rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Expected term Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Intrinsic value of options exercised Closing Stock Price Per Share Closing stock price Closing stock price per share. Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares Resticted common stock non vested -shares Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Unrecognized compensation cost related to non-vested restricted share value Unrecognized Compensation Cost Due In Next Twelve Months Unrecognized compensation cost in fiscal 2016 Amount of the unrecognized compensation cost due in next twelve months. Unrecognized Compensation Cost Due Within Two Years Unrecognized compensation cost in fiscal 2017 Amount of the unrecognized compensation cost due within two years. Unrecognized Compensation Cost Due Within Three Years Unrecognized compensation cost in fiscal 2018 Amount of the unrecognized compensation cost due within three years. Unrecognized Compensation Cost Due Within Four Years Unrecognized compensation cost in fiscal 2019 Amount of the unrecognized compensation cost due within four years. Operating Leases, Future Minimum Payments Due, Next Twelve Months Monthly rent 2016 Operating Leases, Future Minimum Payments, Due in Two Years 2017 Operating Leases, Future Minimum Payments, Due in Three Years 2018 Operating Leases, Future Minimum Payments Due Total Total Product Liability Contingency [Table] Former Chief Executive Officer [Member] Former Chief Executive Officer [Member] Former Chief Executive Officer [Member] Range [Axis] Range [Domain] Minimum [Member] Maximum [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] 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] Other Commitments [Axis] Other Commitments [Domain] Licenses Expire On Two Thousand Eighteen August Ten [Member] Licenses expire on august 10, 2018 [Member] Licenses Expire On Two Thousand Eighteen September Twenty One [Member] Licenses expire on september 21,2018 [Member] Geographical [Axis] Geographical [Domain] NEW YORK Product Liability Contingency [Line Items] Commitments And Contingencies Textuals [Abstract] Commitments and Contingencies (Textuals) Loss Contingency, Damages Sought, Value Compensatory damages Litigation Settlement Collateral Amount Arbitration proceedings, collateral Litigation settlement collateral amount. Payments From Future Revenue From Spectrum Percentage Payments to be made from revenue, percentage Payments from future revenues from spectrum, Percentage. Maximum Future Payment For Wireless Spectrum Licenses Amount of maximum future payment for wireless spectrum licenses Maximum future payment for wireless spectrum licenses. Litigation Settlement, Amount Total Settlement Amounts Aggregated License and settlement, amount Settlement of obligation Percentage Of Amount Recovered From Patent Infringers Paid To Law Firm Recoverable contingency patents allegedly infringed, percentage Percentage of amount recovered from patent infringers paid to law firms. Operating Leases, Rent Expense, Net Annual rent Other Commitments, Description Extended term date, description Payments for Rent Monthly rent Operating Leases, Rent Expense Rental expense, operating leases License Expiration Date License expiration date Date which license is set to establish a new expiration date must be form in CCYY-MM-DD format. Licenses To Be Expired Licenses to be expired Number of licenses to be expired. Lease Agreement Description Lease agreement, description Description of lease agreement. Schedule of Related Party Transactions, by Related Party [Table] 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] Due to Related Parties Balance at beginning of year Balance at end of year Balance at end of year Balance at beginning of year 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 related party. Related Party Transactions (Textual) [Abstract] Related Party Transactions (Textual) Legal Fees Legal expenses Revenues and Gain on Sale [Table] Revenues and gain on sale. Customer [Axis] Customer [Domain] Customer One Member [Member] Customer 1 [Member] Customer one. Customer Two [Member] Customer 2 [Member] Customer two. Customer Three [Member] Customer 3 [Member] Customer three. Revenues and Gain on Sale [Line Items] Revenues and gain on sale. Revenues [Abstract] Summary of revenues and gain on sale Straight Path Spectrum [Member] Straight Path Spectrum [Member] Straight path spectrum. Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Sales Revenue, Net [Member] Sales Revenue [Member] Revenues And Gain On Sale Of Rights In Wireless Spectrum (Textual) [Abstract] Revenues and Gain on Sale of Rights in Wireless Spectrum (Textual) Concentration Risk, Percentage Concentration risk percentage 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 Business Segment Information (Textual) [Abstract] Business Segment Information (Textual) Number of Reportable Segments Reportable Segments Schedule Of Quarterly Financial Data [Abstract] Schedule of quarterly financial data Subsequent Event [Table] Subsequent Event [Line Items] Subsequent Events Textual [Abstract] Subsequent Events (Textual) Subsequent Event, Description Software development agreement, Description