Accounts Payable, Current Accounts payable Accounts Receivable, Net, Current Accounts receivable, less allowance for doubtful accounts of $192,000 at December 31, 2016 and $195,000 at September 30, 2016 Accrued Liabilities, Current Accrued expenses Additional Paid in Capital, Common Stock Capital in excess of par value Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities Total adjustments Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to cash provided by (used in) operating activities: Allowance for Doubtful Accounts Receivable, Current Accounts receivable, allowance for doubtful accounts Amendment Flag Amendment Flag Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Anti-dilutive exercisable stock options, not included in the diluted earnings per share calculation Assets Total Assets Assets [Abstract] ASSETS Assets, Current Total Current Assets Assets, Current [Abstract] Current assets: Represents the percentage carrying value reduction for inventories related to obsolescence, excessive levels, deterioration, possible alternative uses and other factors in determining net realizable value. Inventories are valued at the lower of cost or market, with cost being determined principally by using the last-in, first-out (LIFO) method and market defined as replacement cost for raw materials and net realizable value for work in process and finished goods. Appropriate consideration is given to obsolescence, excessive levels, deterioration, possible alternative uses and other factors in determining net realizable value. The cost of work in process and finished goods includes materials, direct labor, variable costs and overhead. The Company evaluates the need to record inventory adjustments on all inventories, including raw material, work in process, finished goods, spare parts and used equipment. Used equipment acquired by the Company on trade-in from customers is carried at estimated net realizable value. Carrying Value Reduction In Inventory Percentage Carrying value reduction in inventory, percentage Cash and Cash Equivalents, at Carrying Value End of period Beginning of period Cash and cash equivalents Cash and Cash Equivalents [Member] Cash and Money Funds [Member] Cash and Cash Equivalents, Period Increase (Decrease) Net increase (decrease) in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) [Abstract] Cash and cash equivalents at: Class of Stock [Domain] Class of Stock [Domain] Commitments and Contingencies Commitments and contingencies Common and class B stock. common and Class B stock [Member] Common and Class B Stock [Member] Common Class B [Member] Class B Stock [Member] Classification of common stock that is undefined, representing ownership interest in a corporation. Common Class Undefined [Member] Common Stock [Member] Common stock dividend rate percentage. Common Stock Dividend Rate Percentage Stock dividend percentage 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 issued Common Stock, Shares, Outstanding Common stock, shares outstanding Common Stock, Value, Issued Common stock Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Disclosure [Text Block] Customers with 10% (or greater) of Net Revenues Concentration Risk [Line Items] Concentration Risk [Line Items] Concentration Risk, Percentage Percentage of concentration Concentration Risk [Table] Concentration Risk [Table] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Contract Receivable, Due in Next Rolling Twelve Months Billings to date Cost of Revenue Production costs Costs and estimated earnings in excess of billings. Costs And Estimated Earnings In Excess Of Billings [Text Block] Costs and Estimated Earnings in Excess of Billings Costs and estimated earnings on uncompleted contracts. Costs And Estimated Earnings On Uncompleted Contracts Costs and estimated earnings on uncompleted contracts Costs and estimated earnings on uncompleted contracts Costs and Expenses Total costs and expenses Costs and Expenses [Abstract] Costs and expenses: Costs incurred on uncompleted contracts. Costs Incurred on Uncompleted Contracts Costs incurred on uncompleted contracts Costs in Excess of Billings on Uncompleted Contracts or Programs [Abstract] Costs in Excess of Billings on Uncompleted Contracts or Programs [Abstract] Costs in Excess of Billings, Current Costs and estimated earnings in excess of billings Current Fiscal Year End Date Current Fiscal Year End Date Customer Concentration Risk [Member] Entities Owned by One Global Company [Member] Customer Deposits, Current Customer deposits Deferred Tax Liabilities, Net, Noncurrent Deferred and other income taxes Depreciation, Depletion and Amortization Depreciation and amortization Document and entity information. Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Document Information [Line Items] Document Information [Line Items] Document Information [Table] Document Information [Table] Document Period End Date Document Period End Date Document Type Document Type Earnings Per Share [Abstract] Earnings Per Share [Abstract] Earnings Per Share, Basic Net income per share Earnings Per Share, Basic [Abstract] Basic Income per Common Share: Basic: Earnings Per Share, Diluted Net income per share Earnings Per Share, Diluted [Abstract] Diluted Income per Common Share: Diluted: Earnings Per Share [Line Items] Earnings Per Share [Line Items] Earnings Per Share [Line Items] Earnings Per Share [Table] Earnings Per Share [Table] Earnings Per Share [Table] Earnings Per Share [Text Block] Earnings per Share Data Entity Central Index Key Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Filer Category Entity Filer Category Entity Registrant Name Entity Registrant Name Equity Funds [Member] Equities [Member] Estimated Earnings On Uncompleted Contracts Estimated Earnings On Uncompleted Contracts Estimated earnings Exchange Traded Funds [Member] Exchange Traded Funds [Member] Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Transfers of investments between Level 1 and Level 2 Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Company's Assets Measured at Fair Value Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Inputs, Level 1 [Member] Level 1 [Member] Fair Value Measurement, Policy [Policy Text Block] Fair Value Measurements Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income before income tax expense Income Statement [Abstract] Income Statement [Abstract] Income Tax Expense (Benefit) Income tax expense Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accounts Receivable Accounts receivable Increase (Decrease) in Accrued Liabilities Accrued expenses Increase (Decrease) in Billing in Excess of Cost of Earnings Costs and estimated earnings in excess of billings Increase (Decrease) in Customer Deposits Customer deposits Increase (Decrease) in Deferred Income Taxes Deferred income taxes Increase (Decrease) in Inventories Inventories Increase (Decrease) in Operating Capital [Abstract] Changes in assets and liabilities: Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses & other current assets Increase (Decrease) in Trading Securities Change in fair value of marketable securities Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Effect of dilutive stock options Inventory cost basis determination period maximum. Inventory Cost Basis Determination Period Maximum Inventory, maximum time period on the shelf, years Inventory cost basis determination period minimum. Inventory Cost Basis Determination Period Minimum Inventory, minimum time period on the shelf, years Inventory, Current [Table] Inventory, Current [Table] Inventory Disclosure [Abstract] Inventory Disclosure [Abstract] Inventory Disclosure [Text Block] Inventories Inventory, Finished Goods, Net of Reserves Finished goods Inventory [Line Items] Inventory [Line Items] Inventory, Net Inventories, net Inventories, net Inventory, Net [Abstract] Inventory, Net [Abstract] Inventory, Raw Materials, Net of Reserves Raw materials Carrying amount as of the balance sheet date for used equipment. Inventory Used Equipment Used equipment Represents the inventory valuation estimate amount after accounting for inventories related to obsolescence, excessive levels, deterioration, possible alternative uses and other factors in determining net realizable value. Inventories are valued at the lower of cost or market, with cost being determined principally by using the last-in, first-out (LIFO) method and market defined as replacement cost for raw materials and net realizable value for work in process and finished goods. Appropriate consideration is given to obsolescence, excessive levels, deterioration, possible alternative uses and other factors in determining net realizable value. The cost of work in process and finished goods includes materials, direct labor, variable costs and overhead. The Company evaluates the need to record inventory adjustments on all inventories, including raw material, work in process, finished goods, spare parts and used equipment. Used equipment acquired by the Company on trade-in from customers is carried at estimated net realizable value. Inventory Valuation Estimate Inventory valuation estimate Inventory, Work in Process, Net of Reserves Work in process Investment Holdings [Line Items] Investment Holdings [Line Items] Investment Holdings [Table] Investment Holdings [Table] Investment Income, Net Interest and dividend income, net of fees Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Liabilities Total Liabilities Liabilities and Equity Total Liabilities and Shareholders' Equity Liabilities and Equity [Abstract] LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities, Current Total Current Liabilities Liabilities, Current [Abstract] Current Liabilities: Marketable Securities Marketable securities, cost Marketable Securities [Abstract] Marketable Securities [Abstract] Marketable Securities, Current Marketable securities at fair value (cost $86,498,000 at December 31, 2016 and $86,203,000 at September 30, 2016) Total Marketable Securities, Gain (Loss) Realized and unrealized gains (losses) on marketable securities, net Marketable Securities [Table Text Block] Marketable Securities More than five year from balance sheet date and thereafter. More Than Five Year From Balance Sheet Date And Thereafter Member Greater Than Five Years Old Inventory [Member] More than four and within five year from balance sheet date. More Than Four And Within Five Year From Balance Sheet Date [Member] Four to Five Years Old Inventory [Member] More than three and within four year from balance sheet date. More Than Three And Within Four Year From Balance Sheet Date [Member] Three to Four Years Old Inventory [Member] Mutual Fund [Member] Mutual Funds [Member] Net Cash Provided by (Used in) Financing Activities, Continuing Operations Cash flows provided by financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Cash flows from financing activities: Net Cash Provided by (Used in) Investing Activities, Continuing Operations Cash flows used in investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Cash flows from investing activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations Cash flows provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Cash flows from operating activities: Net Income (Loss) Attributable to Parent Net income Net income Net Realized and Unrealized Gain (Loss) on Trading Securities Net unrealized gains (losses) Nonoperating Income (Expense) Other income (expense), net Nonoperating Income (Expense) [Abstract] Other income (expense), net: Operating Income (Loss) Operating income Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Basis of Presentation Other Assets, Noncurrent Other assets Other Nonoperating Income (Expense) Other Payments to Acquire Marketable Securities Purchases of marketable securities Payments to Acquire Productive Assets Capital expenditures 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, Value, Issued Preferred stock, par value $.10 per share; authorized 300,000 shares; none issued Prepaid Expense and Other Assets, Current Prepaid expenses & other current assets Proceeds from Sale and Maturity of Marketable Securities Proceeds from sale and maturity of marketable securities Proceeds from Stock Options Exercised Proceeds from stock option exercises Property, Plant and Equipment, Net Property and equipment, net of accumulated depreciation Provision for Doubtful Accounts Provision for doubtful accounts Range [Axis] Range [Axis] Range [Domain] Range [Domain] Research and Development Expense Product engineering and development Retained Earnings (Accumulated Deficit) Retained earnings Risks and Uncertainties [Abstract] Risks and Uncertainties [Abstract] Sales Revenue, Goods, Net Net revenue Sales Revenue, Net [Member] Revenue [Member] Schedule of cost and estimated earnings in excess of billings on uncompleted contracts. Schedule Of Cost And Estimated Earnings In Excess Of Billings On Uncompleted Contracts Table [Text Block] Costs and Estimated Earnings in Excess of Billings on Uncompleted Contracts Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Basic and Diluted Earnings Per Share Schedule of Inventory, Current [Table Text Block] Net Inventories Schedule of Investments [Abstract] Schedule of Investments [Abstract] Selling, General and Administrative Expense Selling, general and administrative Share-based Compensation Stock-based compensation Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares Exercisable stock options, included in the diluted earnings per share calculation Class of Stock [Axis] Class of Stock [Axis] Statement [Line Items] Statement [Line Items] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Stockholders' Equity Attributable to Parent Total Shareholders' Equity Stockholders' Equity Attributable to Parent [Abstract] Shareholders' equity: Stockholders' Equity Note, Stock Split Stock split ratio description Stockholders' Equity Note, Stock Split, Conversion Ratio Stock split ratio Text Block [Abstract] Text Block [Abstract] Trading Symbol Trading Symbol US Treasury and Government Short-term Debt Securities [Member] Government Securities [Member] Weighted Average Number of Shares Outstanding, Diluted Weighted-average diluted shares outstanding Weighted Average Number of Shares Outstanding, Diluted [Abstract] Common Shares: Weighted Average Number of Shares Outstanding, Basic Weighted-average common shares outstanding