Major Types of Debt and Equity Securities [Axis] Certificates of Deposit [Member] Municipal Bonds [Member] Award Type [Axis] Stock Option Plans [Member] Plan Name [Axis] 2007 Plan [Member] Loss Contingency Nature [Axis] Standby Letters of Credit [Member] Prospective Adoption of New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncement [Member] Employee Stock Ownership Plan (ESOP) Name [Axis] Employee Stock Ownership Plan [Member] 2017 Plan [Member] Award Type [Axis] Non employee directors [Member] Range [Axis] Maximum [Member] Individual Employee [Member] Document And Entity Information [Abstract] Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Filer Category Document Fiscal Period Focus Document Fiscal Year Focus Entity Common Stock, Shares Outstanding Statement of Financial Position [Abstract] ASSETS: Cash and cash equivalents Investment securities Trade accounts receivable, net of allowance of $3,000 Income tax receivable Inventories: Raw materials Work-in-process Costs related to contracts in process, net of advance payments of $173,061 and $1,366,504 at December 31, 2017 and June 30, 2017, respectively Total inventories Deferred tax assets Prepaid expenses and other current assets Total current assets Property, plant and equipment, net Deferred tax assets Total assets LIABILITIES AND STOCKHOLDERS' EQUITY: Accounts payable Accrued expenses: Salaries and wages Vacation ESOP payable Other Payroll and other taxes withheld Income taxes payable Total current liabilities Deferred tax liabilities Total liabilities Commitments and contingencies (see Note 5) Common stock, par value $.33-1/3 per share Authorized 10,000,000 shares; Issued 3,029,874 shares as of December 31, 2017 and June 30, 2017. Outstanding 2,366,523 and 2,371,321 as of December 31, 2017 and June 30, 2017, respectively (includes 37,083 and 45,000 Unearned ESOP shares, respectively) Capital in excess of par value Accumulated other comprehensive loss Retained earnings Total stockholders equity before ESOP Less: Unearned ESOP shares Cost of 663,351 and 658,553 shares of common stock in treasury as of December 31, 2017 and June 30, 2017, respectively Total stockholders' equity Total liabilities and stockholders' equity Trade accounts receivable, allowance Advance payments of costs related to contracts in process Common stock, par value Common stock, shares authorized Common stock, shares issued Common stock, shares outstanding Unearned ESOP, shares Treasury stock, shares Income Statement [Abstract] Net sales Cost of sales Gross profit Selling, general and administrative expenses Operating income Other income Interest income Other Total other income Income before provision for income taxes Provision for income taxes Net income Other comprehensive income, net of tax: Unrealized loss on investment securities Total comprehensive income Net income per share: Basic Diluted Weighted average number of shares outstanding: Basic Diluted Dividends per share: Statement of Cash Flows [Abstract] Cash Flows from Operating Activities: Net income Adjustments to reconcile net income to net cash provided by operating activities: Excess tax benefits from share-based compensation Stock-based compensation Depreciation ESOP compensation expense Loss on disposal of assets Deferred income tax expense Changes in assets and liabilities: (Increase) decrease in trade receivable, net Decrease in income tax receivable Decrease in inventories, net (Increase) decrease in prepaid expenses and other current assets Decrease in accounts payable Increase (decrease) in accrued salaries and wages Decrease in vacation accrual Decrease in ESOP payable Decrease in other accrued expenses Increase in payroll and other taxes withheld Increase in income tax payable Net cash provided by operating activities Cash Flows from Investing Activities: Additions to property, plant and equipment Purchase of investment securities Proceeds from sale/maturity of investment securities Net cash used in investing activities Cash Flows from Financing Activities: Dividends on common stock Purchase of treasury stock Proceeds from exercise of stock options Excess tax benefits from share-based compensation Net cash used in financing activities Decrease in cash and cash equivalents Cash and cash equivalents, beginning of period Cash and cash equivalents, end of period Supplemental Schedule of Cash Flow Information: Income taxes paid Supplemental Schedule of Non-cash Financing Activities: Accrual of dividends Basis of Presentation [Abstract] Basis of Presentation Investments, Debt and Equity Securities [Abstract] Investment Securities Net Income per Share [Abstract] Net Income per Share Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Stock Based Compensation Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Recently Issued Accounting Standards [Abstract] Recently Issued Accounting Standards Employee Stock Ownership Plan [Abstract] Employee Stock Ownership Plan Schedule of Available-for-Sale Securities Schedule of Contractual Maturities Schedule of Fair Value Assumptions Schedule of Stock Option Activity Schedule of Changes in Non-Vested Stock Options Schedule of ESOP shares Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Line Items] Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Contractual maturities of available-for-sale securities Less than One Year One to Five Years Fair Value Anti-dilutive securities Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Title of Individual [Axis] Stock based compensation expense Deferred tax benefit related to stock based compensation Unrecognized compensation costs Period in which compensation cost will be recognized Deferred tax benefit related to unrecognized compensation costs Vesting period Expiration period Authorized shares under plan Granted Outstanding Cash divided paid Percentage of total number of shares subject to options or awards, single fiscal year Number of shares subject to option or award, single fiscal year Total intrinsic values of the options exercised Vested and exercisable shares Stock Based Compensation Schedule Of Weighted Average Assumptions For Option Awards Details Weighted Average Assumptions Dividend yield Company's expected volatility Risk-free interest rate Expected term Weighted average fair value per share of options granted during the period Stock Based Compensation Schedule Of Stock Option Activity Details Number of Shares Subject To Options Balance at July 1, 2017 Exercised Forfeited or expired Outstanding at December 31, 2017 Vested or expected to vest at December 31, 2017 Exercisable at December 31, 2017 Weighted Average Exercise Price Balance at July 1, 2017 Granted Exercised Forfeited or expired Outstanding at December 31, 2017 Vested or expected to vest at December 31, 2017 Exercisable at December 31, 2017 Weighted Average Remaining Contractual Term Outstanding Granted Vested or expected to vest at December 31, 2017 Exercisable at December 31, 2017 Aggregate Intrinsic Value Outstanding at December 31, 2017 Vested or expected to vest at December 31, 2017 Exercisable at December 31, 2017 Number of Shares Subject to Option Non-vested at July 1, 2017 Granted Vested Forfeited or expired Non-vested at December 31, 2017 Weighted Average Grant Date Fair Value (per Option) Non-vested at July 1, 2017 Granted Vested Forfeited or expired Non-vested at December 31, 2017 Statement [Table] Statement [Line Items] Contingent liabilities Prospective Adoption of New Accounting Pronouncements [Table] Item Effected [Line Items] Change in current assets Change in noncurrent liabilities Change in noncurrent assets Schedule of Employee Stock Ownership Plan (ESOP) Disclosures [Table] Employee Stock Ownership Plan (ESOP) Disclosures [Line Items] Number of hours worked per year to quality for the plan Shares repurchased Value of shares repurchased Allocated shares Committed-to-be-released shares Unreleased shares Total shares held by the ESOP Fair value of unreleased shares Represents the amount of dividends accrued in noncash investing or financing activities. Amount of deferred tax benefit attributable to unrecognized share-based compensation. Minimum number of hours worked per year for nonunion employees to participate in ESOP. Information by name of employee stock ownership plan. The entire disclosure for employee stock ownership plan. Weighted average remaining contractual term for option awards granted, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Total of all stockholders' equity (deficit) items, before ESOP and Treasury stock. Name of the equity-based compensation arrangement plan. Name of the equity-based compensation arrangement plan. Cost of unearned shares that qualify as permanent equity that are held by an employee stock ownership plan (ESOP). 2017 Plan [Member] Non employee directors [Member] Individual Employee [Member] The percentage of the total number of shares subject to options or awards granted in a single fiscal year; this will take effect only if the percentage is less than a specified amount in the plan contract. The number of shares subject to option or award in a single fiscal year as outlined in the plan contract. Inventory, Net Assets, Current Deferred Tax Assets, Net of Valuation Allowance Assets Liabilities, Current Liabilities TotalStockholdersEquityBeforyEsopAndTreasuryStock Unearned ESOP Shares Cost Treasury Stock, Value Stockholders' Equity Attributable to Parent Liabilities and Equity Gross Profit Operating Income (Loss) Other Nonoperating Income Nonoperating Income (Expense) Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Comprehensive Income (Loss), Net of Tax, Attributable to Parent Weighted Average Number of Shares Outstanding, Basic Weighted Average Number of Shares Outstanding, Diluted Excess Tax Benefit from Share-based Compensation, Operating Activities Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Increase (Decrease) in Accounts Receivable Increase (Decrease) in Income Taxes Receivable Increase (Decrease) in Inventories Increase (Decrease) in Prepaid Expense and Other Assets Net Cash Provided by (Used in) Operating Activities Payments to Acquire Property, Plant, and Equipment Payments to Acquire Available-for-sale Securities Net Cash Provided by (Used in) Investing Activities Payments of Ordinary Dividends, Common Stock Payments for Repurchase of Common Stock Net Cash Provided by (Used in) Financing Activities Cash and Cash Equivalents, Period Increase (Decrease) Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term 2007 Plan [Member] [Default Label] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value Employee Stock Ownership Plan (ESOP), Shares in ESOP