Amendment Flag Current Fiscal Year End Date Document Period End Date Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Entity Public Float Entity Registrant Name Entity Central Index Key Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Document Type Accounts payable Accrued liabilities Income taxes payable Fixed assets, accumulated depreciation Treasury stock, 3,851,967 and 3,388,589 shares, at cost Additional paid-in capital Adjustments to reconcile net income to net cash provided by operating activities: Share-based compensation expense Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Reversal of deferred tax asset in connection with stock options forfeited Antidilutive Securities [Axis] Anti-dilutive securities excluded from computation of earnings per dilutive share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities, Name [Domain] Assets: Total assets Assets Total current assets Assets, Current Current assets: Total noncurrent assets Assets, Noncurrent Basis of presentation Business Description and Basis of Presentation [Text Block] Capital expenditures funded by accounts payable Decrease in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of period Cash and cash equivalents, end of period Cash and cash equivalents Class of Treasury Stock [Table] Stock repurchase program [Abstract] Class of Stock Disclosures [Abstract] Commitments and contingencies [Abstract] Common stock, shares authorized (in shares) Common stock, par value (in dollars per share) Dividends declared and paid per common share (in dollars per share) Common stock, shares issued (in shares) Common stock, shares outstanding (in shares) Common stock, $0.01 par value, 20,000,000 shares authorized; 11,185,331 and 11,170,881 shares issued, respectively; 7,383,364 and 7,782,292 shares outstanding, respectively Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Cost of sales Credit Facility [Axis] Credit Facility [Domain] Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Deferred stock units [Abstract] Deferred Compensation Arrangements [Abstract] Deferred stock units issued for incentive bonus (in shares) Deferred Compensation Arrangement with Individual, Shares Issued Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] Deferred Stock Units [Member] Deferred Compensation, Share-based Payments [Member] Deferred rent, net of current portion Deferred income tax provision Deferred revenue, net of current portion Deferred revenue Deferred tax assets Deferred Tax Assets, Net of Valuation Allowance, Noncurrent Deferred tax assets Deferred Tax Assets, Net of Valuation Allowance, Current Depreciation and amortization Dividends [Abstract] Dividends declared and paid on common stock Dividends, Common Stock, Cash Earnings per share [Abstract] Earnings Per Share Reconciliation [Abstract] Shares used in per-share calculation: Net income per common share [Abstract] Net income per common share: Earnings per share Basic (in dollars per share) Diluted (in dollars per share) Earnings Per Share, Diluted Earnings per share [Abstract] Effect of exchange rate changes on cash and cash equivalents Effective tax rate Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Domain] Equity, Class of Treasury Stock [Line Items] Incremental tax benefits on stock options exercised Incremental tax benefits from stock options exercised Excess Tax Benefit from Share-based Compensation, Operating Activities Warranties issued Extended Product Warranty Accrual, Increase for Warranties Issued Accrued product warranty liability, long-term Balance, end of period Balance, beginning of period Extended Product Warranty Accrual Warranty [Abstract] Extended Product Warranty Disclosure [Abstract] Warranty settlements Extended Product Warranty Accrual, Decrease for Payments Accrued product warranty liability, current Intangible assets, accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Foreign currency transaction (gains) losses Foreign Currency Transaction Gain (Loss), before Tax Gain on the sale of fixed assets Gain (Loss) on Disposition of Property Plant Equipment Litigation settlement [Abstract] General and administrative Goodwill Gross profit Gross Profit Income taxes [Abstract] Income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest CONSOLIDATED STATEMENTS OF OPERATIONS [Abstract] Income tax provision Income tax provision Income taxes Prepaid income taxes Accrued liabilities and other liabilities Accounts payable Increase (Decrease) in Accounts Payable Prepaid income taxes Increase (Decrease) in Income Taxes Receivable Inventories Increase (Decrease) in Inventories Accounts receivable Increase (Decrease) in Receivables Changes in operating assets and liabilities: Other current and long term assets Increase (Decrease) in Other Operating Assets Increase (Decrease) in Stockholders' Equity [Roll Forward] Add: Dilutive effect of outstanding options as determined by the treasury stock method (in shares) Intangible assets, net of accumulated amortization of $3,024, and $2,779, respectively Interest, net Inventories Inventory Disclosure [Text Block] Inventories [Abstract] Finished goods Inventories Inventories Raw materials and purchased component parts Work-in-process Legal fees associated with lawsuit (Note 7) Liabilities and Shareholders' Equity: Total liabilities Liabilities Total liabilities and shareholders' equity Liabilities and Equity Total noncurrent liabilities Liabilities, Noncurrent Current liabilities: Total current liabilities Liabilities, Current Lender Name [Axis] Line of Credit Facility, Lender [Domain] Litigation Status [Domain] Settlement expenses associated with lawsuit Litigation Status [Axis] Loss Contingency Nature [Axis] Loss Contingencies [Line Items] Loss Contingencies [Table] Loss Contingency, Nature [Domain] Accrued product warranty liability [Roll Forward] Cash flows from financing activities: Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from investing activities: Cash flows from operating activities: Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Net income Net income Net Income (Loss) Attributable to Parent Accounting pronouncements [Abstract] Accounting pronouncements New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Operating income Operating Income (Loss) Operating expenses: Operating expenses Operating Expenses Foreign currency translation adjustment Foreign currency translation adjustment, net of tax Other assets Other current assets Other liabilities Other, net Payment for litigation settlement Purchases of common stock for treasury Payments for Repurchase of Common Stock Payment of dividends on common stock Payment of dividend on common stock Capital expenditures Payments to Acquire Property, Plant, and Equipment Payments to Acquire Software Payments to Acquire Software Revolving credit line borrowings Proceeds from sale of fixed assets Proceeds from stock option exercises Product Warranty Liability [Line Items] Product Warranty Liability [Table] Accrued product warranty liability Accrued product warranty liability [Abstract] Fixed assets, net of accumulated depreciation of $18,991 and $18,336, respectively Accounts receivable, net Revolving credit line payments Repayments of Lines of Credit Engineering, design and product development Retained earnings Net sales Revolving Credit Facility [Member] Settled Litigation [Member] Components of inventory Changes in shareholders' equity Schedule of Stockholders Equity [Table Text Block] Earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Product warranty liability Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Deferred Compensation Arrangement with Individual, Share-based Payments [Table] Selling and marketing Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share-based compensation expense CONSOLIDATED BALANCE SHEETS [Abstract] CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) [Abstract] CONSOLIDATED STATEMENTS OF CASH FLOWS [Abstract] Stock Awards [Member] Stock Compensation Plan [Member] Authorized value of common stock to be repurchased Issuance of shares from exercise of stock options, net of tax benefit Value of common stock repurchased Common stock repurchased (in shares) Issuance of deferred stock units, net of relinquishments Shareholders' equity Total shareholders' equity Beginning balance Balance at December 31, 2017 Stockholders' Equity Attributable to Parent Shareholders' equity: Shareholders' equity [Abstract] Supplemental schedule of non-cash investing activities: Relationship to Entity [Domain] Title of Individual [Axis] Purchase of common stock for treasury Treasury Stock, Value, Acquired, Cost Method Average purchase price of common stock repurchased (in dollars per share) Treasury Stock Acquired, Average Cost Per Share Treasury stock, at cost, 3,801,967 and 3,388,589 shares, respectively Treasury Stock, Value Treasury stock (in shares) Total gross unrecognized tax benefits that would impact the effective rate Previously unrecognized tax benefit recognized Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Basic: Weighted average common shares outstanding (in shares) Basic (in shares) Diluted: Weighted average common and common equivalent shares outstanding (in shares) Diluted (in shares) Shares [Abstract] Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Litigation Case [Axis] Litigation Case [Domain] Maximum [Member] Range [Domain] Range [Axis] Document and Entity Information [Abstract] Civil complaint filed by Avery Dennison Corporation (AD) against the Company and a former employee of the Company alleging that the Company and former employee misappropriated unspecified trade secrets and confidential information from AD related to the design of the Company's food safety terminals. Civil Complaint filed by Avery Dennison Corporation [Member] Complaint alleging misappropriation of unspecified trade secrets and confidential information related to the design of the Company's food safety terminals. Misappropriation of Unspecified Trade Secrets and Confidential Information [Member] Qualification of certain labels for use on the Company's food safety terminals. Qualification of Certain Labels for Use on Food Safety Terminals [Member] TD Bank, N.A. (TD Bank) is a member of TD Bank Group and a subsidiary of The Toronto-Dominion Bank of Toronto, Canada. TD Bank, N.A. [Member] TD Bank [Member] Interest and other income (expense): The amount of interest income and other income (expense) recognized during the period. Interest and Other Income (Expense) Interest and other income (expense) The extended warranty period on company products, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Extended Product Warranty Period Product warranty period Basis of presentation [Abstract] New stock repurchase program approved by the Board of Directors on February 25, 2016, which authorizes the repurchase of up to $5,000,000 of outstanding shares of common stock from time to time in the open market through December 31, 2017, depending on market conditions, share price and other factors. New Stock Repurchase Program [Member] Stock Repurchase Program [Member] The chief executive officer (CEO) is the highest ranking executive officer, who has ultimate managerial responsibility for the entity and who reports to the board of directors. In addition, the CEO may also be the chairman of the board or president. The chief financial officer (CFO) is a senior executive officer responsible for overseeing the financial activities of the entity. Chief Executive Officer and Chief Financial Officer [Member] CEO and CFO [Member]