Class of Stock [Axis] Class A Common Stock, $0.10 par value Convertible Preferred Stock, $20 stated value Noncumulative Preferred Stock [Member] Equity Components [Axis] Preferred Stock [Member] Common Stock Class A [Member] Additional Paid-in Capital [Member] Treasury Stock Common ClassA (Member) AOCI Attributable to Parent [Member] Retained Earnings [Member] Financial Instrument [Axis] Municipal Bonds [Member] Real Estate Investment [Member] Equity Securities [Member] Money Markets and CDs [Member] Measurement Frequency [Axis] Fair Value, Recurring [Member] Fair Value Hierarchy and NAV [Axis] Fair Value, Inputs, Level 1 [Member] Investment Type [Axis] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Money Markets [Member] Statement [Table] Statement [Line Items] Document Type Amendment Flag Amendment Description Document Registration Statement Document Annual Report Document Quarterly Report Document Transition Report Document Shell Company Report Document Shell Company Event Date Document Period Start Date Document Period End Date Document Fiscal Period Focus Document Fiscal Year Focus Current Fiscal Year End Date Entity File Number Entity Registrant Name Entity Central Index Key Entity Primary SIC Number Entity Tax Identification Number Entity Incorporation, State or Country Code Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Three Entity Address, City or Town Entity Address, State or Province Entity Address, Country Entity Address, Postal Zip Code Country Region City Area Code Local Phone Number Extension Written Communications Soliciting Material Pre-commencement Tender Offer Pre-commencement Issuer Tender Offer Title of 12(b) Security No Trading Symbol Flag Trading Symbol Security Exchange Name Title of 12(g) Security Security Reporting Obligation Annual Information Form Audited Annual Financial Statements Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Interactive Data Current Entity Filer Category Entity Small Business Entity Emerging Growth Company Elected Not To Use the Extended Transition Period Document Accounting Standard Other Reporting Standard Item Number Entity Shell Company Entity Public Float Entity Bankruptcy Proceedings, Reporting Current Entity Common Stock, Shares Outstanding Documents Incorporated by Reference [Text Block] Statement of Financial Position [Abstract] ASSETS Current Assets: Cash and cash equivalents Investments and securities Accounts receivable: Trade, net of allowance for credit losses of $29,699 and $12,414 Other Income tax overpayment Federal solar tax credit receivable Inventories, net Prepaid expenses Total Current Assets Property and Equipment, net, at cost Other Assets Investment in Limited Land Partnership, at cost Projects in process Other Total Other Assets Intangible Assets, net TOTAL ASSETS LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Accounts payable, trade Dividends payable Deferred income Accrued expenses Income tax payable Total Current Liabilities Long-Term Liabilities Deferred income taxes Total Long-Term Liabilities Total Liabilities Commitments and Contingencies Stockholders’ Equity Convertible preferred stock, 1,000,000 shares authorized, Series 1—noncumulative, $20 stated value, 25,000 shares authorized, 4,239 issued and outstanding Common stock, Class A, $.10 par value, 10,000,000 shares authorized, 8,502,881 shares issued and outstanding Additional paid-in capital Accumulated other comprehensive income Retained earnings Less: treasury stock, 3,613,827 and 3,610,451 shares, at cost Total Stockholders’ Equity TOTAL LIABILITES AND STOCKHOLDERS’ EQUITY Trade, allowance for credit loss, current Convertible preferred stock, shares authorized Convertible preferred stock, stated value Convertible preferred stock, shares issued Convertible preferred stock, shares outstanding Class A common stock, par value Class A common stock, shares authorized Class A common stock, shares issued Class A common stock, shares outstanding Treasury stock, shares Income Statement [Abstract] Net Sales Less: Cost of Goods Sold Gross Profit Operating Expenses General and Administrative Sales Engineering Total Operating Expenses Income From Operations Other Income (Expense) Other Dividend and Interest Income Unrealized Gain on equity securities Gain on Sale of Investments Gain on Solar Tax Credit (Loss) on Sale of Assets Total Other Income Income Before Provisions for Income Taxes Provisions for Income Taxes: Current Expense Deferred Tax Expense Total Income Tax Expense Net Income Income Per Share of Common Stock Basic Diluted Weighted Average Number of Common Shares Outstanding Basic Diluted Net Income Other Comprehensive Income/(Loss), Net of Tax Unrealized gain (loss) on debt securities: Unrealized holding gains (losses) arising during period Income tax (expense)/benefit related to other comprehensive income Other Comprehensive Income (Loss) Comprehensive Income Balance Balance, shares Purchases of common stock Unrealized gain, net of tax effect Purchases of common stock, shares  Dividend declared at $1.00 per common share outstanding Balance Balance, shares Statement of Stockholders' Equity [Abstract] Dividend per share, declared Statement of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES: Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization (Gain) on sale of investments Unrealized (gain) on equity investments Provision for credit losses on accounts receivable Reserve for obsolete inventory Deferred income taxes Loss on sales of assets Changes in assets and liabilities: (Increase) decrease in: Accounts receivable Inventories Prepaid expenses Other receivables Federal solar tax credit receivable Income tax overpayment Increase (decrease) in: Accounts payable Deferred gain on solar tax credit Accrued expense Income tax payable Net cash from operating activities CASH FLOWS FROM INVESTING ACTIVITIES: (Purchase) of property and equipment Proceeds from sale of marketable securities (Purchase) of marketable securities Distribution from investment in limited land partnership Net cash from investing activities CASH FLOWS FROM FINANCING ACTIVITIES: (Purchase) of treasury stock Dividends paid Net cash from financing activities NET CHANGE IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, beginning of period Cash and Cash Equivalents, end of period Supplemental Disclosure for Cash Flow Information: Cash payments for: Income taxes Interest paid Cash receipts for: Income taxes Pay vs Performance Disclosure [Table] Executive Category [Axis] Individual [Axis] Adjustment to Compensation [Axis] Measure [Axis] Pay vs Performance Disclosure, Table Company Selected Measure Name Named Executive Officers, Footnote Peer Group Issuers, Footnote Changed Peer Group, Footnote PEO Total Compensation Amount PEO Actually Paid Compensation Amount Adjustment To PEO Compensation, Footnote Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Compensation Actually Paid Amount Adjustment to Non-PEO NEO Compensation Footnote Equity Valuation Assumption Difference, Footnote Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Company Selected Measure Total Shareholder Return Vs Peer Group Compensation Actually Paid vs. Other Measure Tabular List, Table Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Net Income (Loss) Company Selected Measure Amount Other Performance Measure, Amount Adjustment to Compensation, Amount PEO Name Name Non-GAAP Measure Description Additional 402(v) Disclosure Pension Benefits Adjustments, Footnote Equity Awards Adjustments, Footnote Erroneously Awarded Compensation Recovery [Table] Restatement Determination Date [Axis] Restatement Determination Date Aggregate Erroneous Compensation Amount Erroneous Compensation Analysis Stock Price or TSR Estimation Method Outstanding Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Not Yet Determined Name Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery, Explanation of Impracticability Name Compensation Amount Restatement does not require Recovery Awards Close in Time to MNPI Disclosures [Table] Award Type [Axis] Award Timing MNPI Disclosure Award Timing Method Award Timing Predetermined Award Timing MNPI Considered Award Timing, How MNPI Considered MNPI Disclosure Timed for Compensation Value Awards Close in Time to MNPI Disclosures, Table Name Underlying Securities Exercise Price Fair Value as of Grant Date Underlying Security Market Price Change Insider Trading Arrangements [Line Items] Material Terms of Trading Arrangement Name Title Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted Adoption Date Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated Termination Date Expiration Date Arrangement Duration Aggregate Available No Insider Trading Flag Insider Trading Policies and Procedures [Line Items] Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Not Adopted Organization, Consolidation and Presentation of Financial Statements [Abstract] Unaudited Interim Financial Statements Investments, Debt and Equity Securities [Abstract] Investments Inventory Disclosure [Abstract] Inventories Earnings Per Share [Abstract] Earnings per Share Retirement Benefits [Abstract] Retirement Benefit Plan Fair Value Disclosures [Abstract] Fair Value Measurements Subsequent Events [Abstract] Subsequent Events Accounting Estimates Significant Accounting Policies Purchase of Transferrable Tax Credits Segment Reporting and Related Information Recently Issued Accounting Pronouncements Schedule of Investments Schedule of Unrealized Loss Breakdown by Investment Type Schedule of Inventories Schedule of Basic and Diluted Earnings Per Share Schedule of Assets Measured at Fair Value on Recurring Basis Purchase of tax credit Exchange for consideration of tax credit Gain on solar tax credit Marketable Securities [Table] Marketable Securities [Line Items] Cost Basis Gross Unrealized Gains Gross Unrealized Losses Fair Value Less than 12 months, Fair Value Less than 12 months, Unrealized Loss 12 months or greater, Fair Value 12 months or greater, Unrealized Loss Total, Fair Value Total, Unrealized Loss Debt securities maturity description Impairment loss Gross realized gain Gross realized losses Gross realized loss debt Gross realized gain debt Raw materials Work in process Finished goods Inventory, gross Less: allowance for obsolete inventory Inventories, net Net income Basic EPS, Income Basic EPS, Shares Basic EPS, Per-Share Amount Effect of dilutive Convertible Preferred Stock, Income Effect of dilutive Convertible Preferred Stock, Shares Effect of dilutive Convertible Preferred Stock, Per-Share Amount Diluted EPS, Income Diluted EPS, Shares Diluted EPS, Per-Share Amount Description of employees eligibility Employees vesting percentage Employees matching contributions Fair Value, Recurring and Nonrecurring [Table] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Total fair value of assets measured on a recurring basis Convertible Preferred Stock, $20 stated value [Member] Class A Common Stock, $0.10 par value [Member] Federal solar tax credit receivable. Income tax overpayment. Engineering expenses. Gain loss on solar tax credit. Common Stock Class A [Member] Treasury Stock Common ClassA (Member). Increase decrease federal solar tax credit receivable. Increase decrease deferred gain on solar tax credit. Cash Payment For [Abstract] Cash Receipts For [Abstract] Increase decrease inIncome tax overpayment. Purchase Of Transferrable Tax Credits [Policy Text Block] Money Markets and CDs [Member] Impairment of investment. Tabular disclosure of unrealized gains and losses on investments. Per share included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible preferred stock using the if-converted method. Income taxes receipts. No Insider Trading Flag Money Markets [Member] Assets, Current Real Estate Investments, Other Real Estate Investment Property, at Cost Assets Liabilities, Current Liabilities, Noncurrent Liabilities Treasury Stock, Value Equity, Attributable to Parent Liabilities and Equity Cost of Product and Service Sold Gross Profit Operating Expenses [Default Label] Operating Income (Loss) Other Nonoperating Income Nonoperating Income (Expense) Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income Tax Expense (Benefit) OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, Tax OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Comprehensive Income (Loss), Net of Tax, Attributable to Parent Shares, Outstanding Stock Repurchased During Period, Value Adjustments to Additional Paid in Capital, Dividends in Excess of Retained Earnings Unrealized Gain (Loss) on Investments Deferred Other Tax Expense (Benefit) Increase (Decrease) in Accounts Receivable Increase (Decrease) in Inventories Increase (Decrease) in Prepaid Expense Increase (Decrease) in Other Receivables IncreaseDecreaseFederalSolarTaxCreditReceivable IncreaseDecreaseInIncomeTaxOverpayment Increase (Decrease) in Income Taxes Payable Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Payments to Acquire Property, Plant, and Equipment Payments to Acquire Marketable Securities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Payments for Repurchase of Other Equity Payments of Dividends Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation IncomeTaxesReceipts Forgone Recovery, Individual Name Outstanding Recovery, Individual Name Awards Close in Time to MNPI Disclosures, Individual Name Trading Arrangement, Individual Name Debt Securities, Available-for-Sale, Unrealized Loss Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss Inventory, Gross Inventory Valuation Reserves