Document and Entity Information [Abstract] Statement [Table] Equity Components [Axis] Equity Component [Domain] Common Stock [Member] Common Stock 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 $0 and $0, respectively Due from Related Parties, Current Due from settlement Prepaid Expense, Current Prepaid expenses - related to settlements and licensing Deferred Tax Assets, Net, Current 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 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 Class A common stock, $0.01 par value; 2,000 shares authorized; 787 shares issued and outstanding Additional Paid in Capital Additional paid-in capital Retained Earnings (Accumulated Deficit) Retained earnings Accumulated deficit Treasury Stock, Value Number of shares held in treasury stock, value Treasury stock, 42 shares at cost Stockholders' Equity Attributable to Parent Total Straight Path Communications Inc. 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 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 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) Income (loss) from operations Loss from operations Income (loss) from operations Other Income and Expenses [Abstract] Other income: Interest Income, Other Interest income Other Income Other income Income From Payments Of Liabilities Income from IDT Corporation payments of liabilities Income from payments of liabilities. Interest and Other Income Total other income Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Income (loss) before income taxes Income (loss) before income taxes Income Tax Expense (Benefit) Provision for income taxes PROVISION FOR INCOME TAXES Provision for (income taxes) income tax benefits Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income Net income (loss) Net income (loss) Income (Loss) Attributable to Noncontrolling Interest Net loss attributable to noncontrolling interests Net (income) loss attributable to noncontrolling interests Net Income (Loss) Attributable to Parent Net loss Net (loss) income Net income (loss) attributable to Straight Path Communications Inc. Earnings (loss) per ahare attributable to Straight Path Communications Inc. stockholders: Earnings (loss) per share attributable to Straight Path Communications Inc. stockholders: Earnings Per Share, Basic Basic Earnings 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 Diluted weighted-average number of shares Statement of Stockholders' Equity [Abstract] Additional Paid-in Capital [Member] Additional Paid-in Capital Retained Earnings [Member] Retained Earnings Treasury Stock [Member] Treasury Stock Noncontrolling Interest [Member] Noncontrolling Interest Shares, Outstanding Balances (in shares) Beginning balance, Shares Ending balance, Shares Ending balance, Shares Stock Issued During Period, Value, Share-based Compensation, Gross Common stock issued for compensation Common stock issued for compensation Common stock 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 upon exercise 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 Common Stock Withheld For Tax Purposes Common stock withheld for payroll 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, Shares, Treasury Stock Reissued Sale of treasury stock, Shares 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, 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 income (loss) to net cash (used in) provided by operating activities: Share-based Compensation Stock-based compensation Stock-based compensation Increase (Decrease) in Operating Capital [Abstract] Changes in assets and liabilities: Increase (Decrease) in Accounts Receivable Trade accounts receivable, net Trade accounts receivable, net Increase (Decrease) Due from Affiliates Due from settlement Due from settlement Increase (Decrease) in Prepaid Expense Prepaid expenses - settlements Prepaid expenses - settlements and licensing Increase (Decrease) in Other Current Assets Other current assets Other current assets Increase (Decrease) in Prepaid Expense and Other Assets Other assets 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 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) Financing Activities [Abstract] Financing activities: Proceeds from Sale of Treasury Stock 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 used in 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 Purchase Of Intangibles Purchase of intangibles Purchase of intangibles. Supplemental cash flow information [Abstract] Supplemental cash flow information Income Taxes Paid, Net Cash paid during the period for income taxes Basis of Presentation and Summary of Significant Accounting Policies and Recent Pronouncements [Abstract] Basis of Presentation [Abstract] Business Description and Basis of Presentation [Text Block] Basis of Presentation Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies and Recent Pronouncements Stockholders' Equity Note Disclosure [Text Block] Equity Earnings (Loss) Per Share [Abstract] (Loss) earnings per share attributable to Straight Path Communications Inc. stockholders: Earnings Per Share [Text Block] Earnings (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 Risk Disclosure [Text Block] Concentration of Customers Income Taxes [Abstract] Income Tax Disclosure [Text Block] Income Taxes 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 Due From Settlement [Abstract] Due From Settlement [Text Block] Due From Settlement The entire disclosure for due from settlement. New Accounting Pronouncements, Policy [Policy Text Block] Summary of Significant Accounting Policies and Recent Pronouncements 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 Related Party Transactions [Table Text Block] Schedule of expenses incurred on related party transactions Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block] Scheudle of revenues from transactions with single customer 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 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] Subsidiary of Limited Liability Company or Limited Partnership [Line Items] Description of Business and Summary of Significant Accounting Policies (Textual) [Abstract] Basis of Presentation (Textual) Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions Ownership in straight path spectrum Schedule of Stock by Class [Table] Related Party Transaction [Axis] Related Party Transaction [Domain] Title of Individual [Axis] Relationship to Entity [Domain] Director [Member] Director [Member] Chief Executive Officer [Member] Davidi Jonas [Member] Officer [Member] Officer [Member] Chief Financial Officer [Member] Jonathan Rand [Member] Non Employee Director [Member] Non Employee Director [Member] Non Employee Director. Chief Technology Officer [Member] Zhouyue (Jerry) Pi [Member] Chief technology officer. Option Indexed to Issuer's Equity, Type [Axis] Option Indexed to Issuer's Equity, Type [Domain] Employee Stock Option [Member] Stock options [Member] Shares underlying stock options [Member] Class of Stock [Line Items] Equity (Textual) [Abstract] Equity (Textual) Equity (Textual) 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, Shares, Restricted Stock Award, Forfeited Number of restricted shares issued to former employees 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 Treasury stock repurchased value. Stock Issued During Period, Shares, Employee Stock Purchase Plans Additional shares issued for amendment of stock option and incentive plan Allocated Share-based Compensation Expense Stock-based compensation expense Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Number of restricted shares issued, shares Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Number of restricted shares issued, value 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 Dividends Dividend declared Payments to Noncontrolling Interests Amount paid to minority shareholders Dividends Payable Unpaid dividends Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic and Diluted weighted-average number of shares [Abstract] Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Effect of dilutive securities: