Condensed Consolidated Balance Sheets Condensed Consolidated Balance Sheets [Abstract] ASSETS: ASSETS: [Abstract] Current assets: Current assets: [Abstract] Cash and cash equivalents Marketable securities Accounts receivable, net of allowance for doubtful accounts of $355 at January 31, 2013 and $400 at April 30, 2012 Costs and estimated earnings in excess of billings, net Inventories Deferred income taxes Prepaid expenses and other Total current assets Property, plant and equipment, at cost ,less accumulated depreciation and amortization Deferred income taxes Goodwill and other intangible assets Cash Surrender Value Of Life Insurance And Cash Held In Trust Cash surrender value of life insurance and cash held in trust Investment in affiliates Other assets Total assets LIABILITIES AND STOCKHOLDERS' EQUITY: LIABILITIES AND STOCKHOLDERS' EQUITY: [Abstract] Current liabilities: Current liabilities: [Abstract] Short-term credit obligations Accounts payable - trade Accrued liabilities Income taxes payable Total current liabilities Capital lease obligation- noncurrent Deferred compensation Deferred Rent And Other Long Term Liabilities Noncurrent Deferred rent and other liabilities Total liabilities Commitments and contingencies Stockholders' equity: Stockholders' equity: [Abstract] Preferred stock -$1.00 par value Common stock-$1.00 par value, issued 9,163,940 shares Additional paid-in capital Retained earnings Common stock reacquired and held in treasury - at cost (732,554 shares at January 31, 2013 and 800,787 shares at April 30, 2012) Accumulated other comprehensive income Total stockholders' equity Total liabilities and stockholders' equity Allowance for doubtful accounts (in Dollars) Preferred stock, par value (in Dollars per share) Common stock par value (in Dollars per share) Common stock, shares issued (in Shares) Treasury stock, shares (in Shares) Condensed Consolidated Statements of Income and Comprehensive Income Condensed Consolidated Statements of Income and Comprehensive Income [Abstract] Revenues Cost of revenues Gross margin Selling and administrative expenses Research and development expense Operating profit Other income (expense): Other income (expense): [Abstract] Investment income Equity loss Impairment of investment in and loans receivable from affiliate Interest expense Other expense, net Income before provision for income taxes Provision for income taxes Net income Net income per common share Net income per common share [Abstract] Basic (in Dollars per share) Diluted (in Dollars per share) Weighted average shares outstanding Weighted average shares outstanding [Abstract] Basic (in Shares) Diluted (in Shares) Comprehensive Income Comprehensive Income [Abstract] Net income Other comprehensive income (loss): Other comprehensive income (loss): [Abstract] Foreign currency translation adjustment Change in market value of marketable securities Deferred tax effect of change in marketable securities Total other comprehensive income (loss) Comprehensive income Condensed Consolidated Statements of Cash Flows Condensed Consolidated Statements of Cash Flows [Abstract] Cash flows from operating activities: Cash flows from operating activities: [Abstract] Non-cash charges to earnings, net Net changes in operating assets and liabilities Net cash provided by operating activities Cash flows from investing activities: Cash flows from investing activities: [Abstract] Proceeds from sale of marketable securities Purchase of marketable securities Loan to affiliate Purchase of fixed assets Net cash used in investing activities Cash flows from financing activities: Cash flows from financing activities: [Abstract] Proceeds from short-term credit obligations Debt payments Payment of cash dividend Exercise of stock options Net cash (used in) provided by financing activities Net increase (decrease) in cash and cash equivalents Net increase (decrease) in cash and cash equivalents [Abstract] Cash and Cash Equivalents, Period Increase (Decrease) Before Adjustment before effect of exchange rate changes Effect of exchange rate changes Effect of exchange rate changes [Abstract] on cash and cash equivalents Net increase (decrease) in cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Supplemental disclosures of cash flow information: Supplemental disclosures of cash flow information: [Abstract] Cash paid during the period for: Cash paid during the period for: [Abstract] Interest Income Taxes NOTE A - CONSOLIDATED FINANCIAL STATEMENTS Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] NOTE B - EARNINGS PER SHARE Earnings Per Share [Text Block] NOTE C - COSTS AND ESTIMATED EARNINGS IN EXCESS OF BILLINGS, NET Long-term Contracts or Programs Disclosure [Text Block] NOTE D - TREASURY STOCK TRANSACTIONS Treasury Stock [Text Block] NOTE E - INVENTORIES Inventory Disclosure [Text Block] NOTE F - SEGMENT INFORMATION Segment Reporting Disclosure [Text Block] Note G - INVESTMENT IN MORION, INC. Investment Holdings [Text Block] NOTE H - ACQUISITION OF ELCOM TECHNOLOGIES, INC. Business Combination Disclosure [Text Block] NOTE I - FAIR VALUE OF FINANCIAL INSTRUMENTS Fair Value Disclosures [Text Block] NOTE J - VALUATION ALLOWANCE ON DEFERRED TAX ASSETS Income Tax Disclosure [Text Block] NOTE K - SPECIAL DIVIDEND Stockholders' Equity Note Disclosure [Text Block] NOTE L - RECENTLY ISSUED ACCOUNTING PROUNCEMENTS Description of New Accounting Pronouncements Not yet Adopted [Text Block] Schedule of Earnings Per Share Reconciliation [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Cost and Estimated Earnings on Uncompleted Contracts Costs and Estimated Earnings in Excess of Billings, Net [Table Text Block] Schedule of Inventory, Current [Table Text Block] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Reconciliation of Assets from Segment to Consolidated [Table Text Block] Business Acquisition, Pro Forma Information [Table Text Block] Available-for-sale Securities [Table Text Block] Unrealized Gain (Loss) on Investments [Table Text Block] Fair Value, by Balance Sheet Grouping [Table Text Block] Schedule of Earnings Per Share Reconciliation Schedule of Earnings Per Share Reconciliation [Abstract] Weighted average shares outstanding: Weighted average shares outstanding: [Abstract] Basic Effect of dilutive securities Diluted Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Abstract] Antidilutive Securities, Name [Domain] Outstanding options and SARS excluded Costs and Estimated Earnings in Excess of Billings, Net Costs and Estimated Earnings in Excess of Billings, Net [Abstract] Costs and estimated earnings in excess of billings Billings in excess of costs and estimated earnings Net asset Schedule of Inventory, Current Schedule of Inventory, Current [Abstract] Raw Materials and Component Parts Work in Progress Finished Goods Reconciliation of Operating Profit (Loss) from Segments to Consolidated Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract] Segment [Domain] Revenues: Revenues: [Abstract] Operating income (loss): Operating income (loss): [Abstract] Operating profit (loss) Reconciliation of Assets from Segment to Consolidated Reconciliation of Assets from Segment to Consolidated [Abstract] Identifiable assets: Identifiable assets: [Abstract] Assets Assets (in Dollars) Business Acquisition, Pro Forma Information Business Acquisition, Pro Forma Information [Abstract] Revenues Business Acquisition, Pro Forma Operating Income (Loss) Operating profit Net income Earnings per share- basic (in Dollars per share) Earnings per share- diluted (in Dollars per share) Costs, Gross Unrealized Gains, Gross Unrealized Losses and Fair Market Value of Available-For-Sale Securities Costs, Gross Unrealized Gains, Gross Unrealized Losses and Fair Market Value of Available-For-Sale Securities [Abstract] Fair Value, Option, Eligible Item or Group [Domain] Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Fair Value and Unrealized Losses, Aggregated by Investment Type and Length of Time Individual Securities have been Continuious Unrealized Loss Position Fair Value and Unrealized Losses, Aggregated by Investment Type and Length of Time Individual Securities have been Continuious Unrealized Loss Position [Abstract] Major Types of Debt and Equity Securities [Domain] Fair Value, Less than 12 months Unrealized Losses, Less than 12 months Fair Value, More than 12 months Unrealized Losses, More than 12 months Fair Value Unrealized Losses April 30, 2012 April 30, 2012 [Abstract] Maturities of Fixed Income Securities Classified as Available-For-Sale Maturities of Fixed Income Securities Classified as Available-For-Sale [Abstract] Current Due after one year through five years Due after five years through ten years Change in Accounting Estimate, Type [Domain] Equity Component [Domain] Stock Issued During Period Shares 401 K Contribution Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Stock Issued During Period, Shares, 401(k) Contribution Segment, Geographical [Domain] Inventory, Net Number of Reportable Segments Number Of Principal Markets Number of Principal Markets Investment [Domain] Cost Method Investment Ownership Percentage Related Party Transaction, Purchases from Related Party Revenue from Related Parties Due to Related Parties, Current Due from Related Parties, Current Minimum Number Of Rubidium Oscillators To Be Produced Per Year Under Agreement Terms License And Equipment Fee Receivable Percentage Of Royalties Payable On Third Party Sales Royalty Payable Period Minimum Worth Of Rubidium Oscillators Proceeds from License Fees Received Cost Method Investment, Ownership Percentage Minimum Number Of Rubidium Oscillators To Be Produced Per Year Under Agreement Terms License And Equipment Fee Receivable Percentage of royalties payable on third party sales Royalty payable period This elements represents the minimum worth of the Rubidium Oscillators. Financing [Domain] Business Acquisition, Acquiree [Domain] Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Business Acquisition, Percentage of Voting Interests Acquired Business Acquisition, Cost of Acquired Entity, Cash Paid Receivable Transfer To Investment Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value Fair Value Inputs, Control Premium Business Acquisition, Purchase Price Allocation, Tangible Assets Business Acquisition Purchase Price Allocatioin Deferred Tax Asset Business Acquisition Purchase Price Allocation Intangible Assets and Goodwill Business Acquisition, Purchase Price Allocation, Goodwill Amount Gain (Loss) on Investments Other than Temporary Impairment Losses, Investments Additional Allowance For Investment Against Notes Receivable Sales Revenue, Goods, Net Professional Fees Interest Income, Other Receivable Transfer to Investment Business Acquisition Purchase Price Allocatioin Deferred Tax Asset Business Acquisition, Purchase Price Allocation, Intangible Assets and Goodwill Amount of additional allowance for investment against the notes receivable. Types of Financial Instruments [Domain] Proceeds from Sale and Maturity of Marketable Securities Available-for-sale Securities, Gross Realized Gains Deferred Tax Assets, Valuation Allowance Dividends Payable, Date Declared Common Stock, Dividends, Per Share, Cash Paid (in Dollars per share) Dividends Payable, Date to be Paid Dividends Payable, Date of Record Settlement of Debt [Member] Scenario [Axis] Business Segments [Axis] Equity Components [Axis] Geographical [Axis] Equity Securities [Member] Financing [Axis] Contracts Accounted for under Percentage of Completion [Member] Fixed Income Securities [Member] Treasury Stock [Member] Antidilutive Securities [Axis] Investment [Axis] Scenario, Unspecified [Domain] Stock Options [Member] Major Types of Debt and Equity Securities [Axis] Financial Instrument [Axis] Corporate [Member] Business Acquisition [Axis] Eligible Item or Group for Fair Value Option [Axis] Change in Accounting Estimate by Type [Axis] Frequency Electronics Inc New York [Member] Frequency Electronics Inc New York [Member] Frequency Electronics Inc New York [Member] United States [Member] United States [Member] Frequency Electronics Inc New York China [Member] Frequency Electronics Inc New York China [Member] Frequency Electronics Inc New York China [Member] Frequency Electronics Inc Zyfer [Member] Frequency Electronics Inc Zyfer [Member] Frequency Electronics Inc Zyfer [Member] Elcom Technologies Inc [Member] Elcom Technologies Inc [Member] Elcom Technologies Inc [Member] Morion Inc [Member] Morion Inc [Member] Morion Inc [Member] China [Member] China [Member] Available For Sale Securities [Member] Available-for-Sale Securities [Member] Common Stock Shares [Member] Common Stock Shares [Member] The most subordinated ownership interest in a corporation - Number of Shares FEI Elcom [Member] FEI-Elcom [Member] FEI-Elcom [Member] Gillam Frequency Electronics Inc [Member] Gillam Frequency Electronics Inc [Member] Gillam Frequency Electronics Inc [Member] Belgium [Member] Belgium [Member] Inter Segment [Member] Inter Segment [Member] Inter Segment [Member] Document and Entity Information [Abstract] BusinessAcquisitionPurchasePriceAllocatioinDeferredTaxAsset BusinessCombinationDisclosureTextBlockAbstract StockholdersEquityNoteDisclosureTextBlockAbstract CostMethodInvestmentOwnershipPercentage LicenseAndEquipmentFeeReceivable BusinessAcquisitionPurchasePriceAllocationIntangibleAssetsAndGoodwill IncomeTaxDisclosureTextBlockAbstract InvestmentHoldingsTextBlockAbstract SegmentReportingDisclosureTextBlockAbstract EarningsPerShareTextBlockAbstract OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlockAbstract DescriptionOfNewAccountingPronouncementsNotYetAdoptedTextBlockAbstract StockIssuedDuringPeriodSharesFourZeroOneKContribution CostAndEstimatedEarningsOnUncompletedContractsTableTextBlock LongTermContractsOrProgramsDisclosureTextBlockAbstract MinimumWorthOfRubidiumOscillators ReceivableTransferToInvestment RoyaltyPayablePeriod FairValueDisclosuresTextBlockAbstract CashAndCashEquivalentsPeriodIncreaseDecreaseBeforeAdjustment TreasuryStockTextBlockAbstract MinimumNumberOfRubidiumOscillatorsToBeProducedPerYearUnderAgreementTerms PercentageOfRoyaltiesPayableOnThirdPartySales NumberOfPrincipalMarkets InventoryDisclosureTextBlockAbstract AdditionalAllowanceForInvestmentAgainstNotesReceivable Available-for-sale Securities, Gross Realized Gains Other Comprehensive Income (Loss), Net of Tax Deferred Tax Assets, Net of Valuation Allowance, Noncurrent Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Net Cash Provided by (Used in) Investing Activities Document Period End Date Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Billings in Excess of Cost Amendment Flag Inventory Disclosure [Text Block] Dividends Payable, Date to be Paid Entity Central Index Key Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value Sales Revenue, Goods, Net Net Cash Provided by (Used in) Financing Activities Deferred Tax Assets, Valuation Allowance Investment Holdings [Text Block] Business Acquisition, Pro Forma Net Income (Loss) Payments of Dividends Treasury Stock [Text Block] Document Fiscal Year Focus Business Acquisition, Pro Forma Revenue Common Stock, Dividends, Per Share, Cash Paid Stockholders' Equity Note Disclosure [Text Block] Other than Temporary Impairment Losses, Investments Liabilities and Equity Fair Value Inputs, Control Premium Entity Current Reporting Status Earnings Per Share [Text Block] Dividends Payable, Date of Record Dividends Payable, Date Declared Stockholders' Equity Attributable to Parent Due from Related Parties, Current Schedule of Inventory, Current [Table Text Block] Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Amendment Description Document Type Business Combination Disclosure [Text Block] Treasury Stock, Value Due to Related Parties, Current Unrealized Gain (Loss) on Investments [Table Text Block] Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Fair Value, by Balance Sheet Grouping [Table Text Block] Asset Impairment Charges Liabilities, Current Repayments of Debt Business Acquisition, Cost of Acquired Entity, Cash Paid Revenue from Related Parties Net Cash Provided by (Used in) Operating Activities Schedule of Earnings Per Share Reconciliation [Table Text Block] Business Acquisition, Pro Forma Information [Table Text Block] Segment Reporting Disclosure [Text Block] Payments to Acquire Marketable Securities Cash and Cash Equivalents, Period Increase (Decrease) Assets, Current Gain (Loss) on Investments Professional Fees Description of New Accounting Pronouncements Not yet Adopted [Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Payments to Acquire Property, Plant, and Equipment Income Tax Disclosure [Text Block] Entity Common Stock, Shares Outstanding Proceeds from License Fees Received Comprehensive Income (Loss), Net of Tax, Attributable to Parent Business Acquisition, Purchase Price Allocation, Goodwill Amount Entity Filer Category Entity Public Float Available-for-sale Securities [Table Text Block] Reconciliation of Assets from Segment to Consolidated [Table Text Block] Entity Voluntary Filers Assets Entity Registrant Name Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage Interest Income, Other Business Acquisition, Percentage of Voting Interests Acquired Entity Well-known Seasoned Issuer Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax Business Acquisition, Purchase Price Allocation, Tangible Assets Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Related Party Transaction, Purchases from Related Party Number of Reportable Segments Gross Profit Liabilities Current Fiscal Year End Date Document Fiscal Period Focus Fair Value Disclosures [Text Block] Interest Expense Long-term Contracts or Programs Disclosure [Text Block] Statement [Table] Statement [Line Items]