Document Type Document Type Other income, net Other Nonoperating Income (Expense) Patents and other assets, net Patent and Other Assets, Net Contingencies Commitments and Contingencies Disclosure [Text Block] Germany GERMANY Deferred Tax Liability Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Segments [Axis] Segments [Axis] Business acquisition agreement, value Business Acquisition Agreement, Value Business Acquisition Agreement, Value Schedule of AOCI Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] In-Process R&D In Process Research and Development [Member] Thereafter Lessee, Operating Lease, Liability, to be Paid, Due after Year Four Lessee, Operating Lease, Liability, to be Paid, Due after Year Four Level 3 Fair Value, Inputs, Level 3 [Member] Repurchases of common stock (in shares) Stock repurchased (in shares) Stock Repurchased During Period, Shares Restricted period, maximum Share Based Compensation, Restricted Period Due between one and five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Exclusive Licensing Agreement Licensing Agreements [Member] Range [Domain] Statistical Measurement [Domain] LIABILITIES AND SHAREHOLDERS’ INVESTMENT Liabilities and Equity [Abstract] Credit Agreement Line of Credit [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] DEFERRED INCOME TAXES Deferred Income Tax Liabilities, Net Security Exchange Name Security Exchange Name Intangible assets, net Intangible assets, net Intangible Assets, Net (Excluding Goodwill) HomeLink® Trade Names and Trademarks Trademarks and Trade Names [Member] ESPP discount rate Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date Proceeds from borrowings on Credit Agreement Proceeds from Issuance of Long-term Debt Income from operations Income from operations Operating Income (Loss) Total current liabilities Liabilities, Current Amounts Reclassified from Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Member] Lease Liabilities Assets And Liabilities, Lessee [Table Text Block] Assets And Liabilities, Lessee Performance Shares Performance Shares [Member] Prepaid expenses and other Prepaid Expense and Other Assets, Current Other Segment OtherSegmentMember Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Repurchases of common stock Payments for Repurchase of Common Stock ASSETS Assets [Abstract] Investment, Name [Axis] Investment, Name [Axis] Option vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Entity Address, State or Province Entity Address, State or Province Accounts payable Accounts Payable, Current Comprehensive Income Comprehensive Income (Loss) Note [Text Block] Activity in available-for-sale securities: Proceeds from Sale and Maturity of Debt Securities, Available-for-sale [Abstract] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Retained earnings Retained Earnings (Accumulated Deficit) 2022 Lessee, Operating Lease, Liability, to be Paid, Year One 2025 Lessee, Operating Lease, Liability, to be Paid, Year Four Automotive Products AutomotiveProductsMember Unrecognized compensation cost Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Due over five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Years, Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Years, Fair Value AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Other Products OtherProductsMember Total operating expenses Operating Expenses OTHER NON-CURRENT LIABILITIES Other Liabilities, Noncurrent Investment income Investment Income, Nonoperating Acquired Finite-Lived Intangible Assets [Line Items] Acquired Finite-Lived Intangible Assets [Line Items] Stock-based compensation expense related to stock options, employee stock purchases and restricted stock APIC, Share-based Payment Arrangement, Increase for Cost Recognition Inventories Total Inventory Inventory, Net NET SALES Revenue Revenue from Contract with Customer, Excluding Assessed Tax Business Acquisition [Axis] Business Acquisition [Axis] Geographical [Domain] Geographical [Domain] Statement [Line Items] Statement [Line Items] Statement [Table] Statement [Table] Range [Axis] Statistical Measurement [Axis] Guardian Optical Technologies Guardian Optical Technologies [Member] Guardian Optical Technologies Business Combinations [Abstract] Entity Small Business Entity Small Business Employee Stock Option Plan EmployeeStockOptionPlanMember Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Debt and Financing Arrangements Debt Disclosure [Text Block] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Issuance of common stock from stock plan transactions Proceeds from Issuance of Common Stock Selling, General and Administrative Expenses Selling, General and Administrative Expenses [Member] Goodwill [Roll Forward] Goodwill [Roll Forward] Amendment Flag Amendment Flag Schedule of Earnings Per Share Basic And Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Schedule of Recognized Identified Assets Acquired and Liabilities Assumed Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Investment Securities Stated at Fair Value Fair Value, Assets Measured on Recurring Basis [Table Text Block] HomeLink Modules HomeLinkModulesMember Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Entity Central Index Key Entity Central Index Key Financial Instruments [Domain] Financial Instruments [Domain] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Aggregate Fair Value of Investments, Loss duration greater than one year Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer Geographical [Axis] Geographical [Axis] Shares issued under the Omnibus plan Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table] Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table] Segments [Domain] Segments [Domain] Unrealized Gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Aggregate Fair Value of Investments, Total Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value Statement of Cash Flows [Abstract] Additional weighted average dilutive common stock equivalents (in shares) Weighted Average Number Diluted Shares Outstanding Adjustment Income Statement Location [Axis] Income Statement Location [Axis] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Income Statement Location [Domain] Income Statement Location [Domain] 2023 Lessee, Operating Lease, Liability, to be Paid, Year Two Selling, general & administrative Selling, General and Administrative Expense Other Other Debt Obligations [Member] Amortization of intangible assets Amortization of Intangible Assets 2024 Lessee, Operating Lease, Liability, to be Paid, Year Three Total other assets Other Assets, Noncurrent Plan Name [Axis] Plan Name [Axis] Segment Reporting Segment Reporting Disclosure [Text Block] Issuance of common stock from stock plan transactions Stock Issued During Period, Value, New Issues Cash & Cash Equivalents Cash and Cash Equivalents, Fair Value Disclosure Total assets Assets Title of 12(b) Security Title of 12(b) Security Omnibus Incentive Plan Omnibus Incentive Plan [Member] Omnibus Incentive Plan Finite-lived intangible assets, net Finite-Lived Intangible Assets, Net Weighted average grant-date fair value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Investments, Debt and Equity Securities [Abstract] OTHER INCOME Investment Income, Nonoperating [Abstract] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Depreciation and amortization Depreciation, Depletion and Amortization Short-Term Investments Short-term Investments [Member] Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value of Investment Securities Unrealized Gain (Loss) on Investments [Table Text Block] Product and Service [Axis] Product and Service [Axis] Total liabilities Liabilities Investment Type [Axis] Investment Type [Axis] Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Less imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Other Other Segments [Member] Patents and Other Intangible Assets PatentsandOtherIntangibleAssetsMember Commitments and Contingencies Disclosure [Abstract] Level 1 Fair Value, Inputs, Level 1 [Member] Inventories Increase (Decrease) in Inventories Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Accounts payable Increase (Decrease) in Accounts Payable Vaporsens Inc Vaporsens Inc [Member] Vaporsens Inc Additional  Paid-In Capital Additional Paid-in Capital [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Japan JAPAN Accrued liabilities, excluding dividends declared and short-term debt Increase (Decrease) in Accrued Liabilities Revenue from Contract with Customer [Abstract] Initial investment in Argil Equity Method Investments Beginning balance (in shares) Ending balance (in shares) Common Stock, Shares, Outstanding Income Tax Disclosure [Abstract] Automotive Products AutomotiveProductsSegmentMember Revolving Facility Revolving Credit Facility [Member] Engineering, research and development Research and Development Expense Acquisition of businesses, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Ownership percentage of business acquisition Business Acquisition, Percentage of Voting Interests Acquired Swing Loans Swing Loans [Member] Operating lease, liability, noncurrent, statement of financial position Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] Schedule of Automotive and Other Segment Reporting Schedule of Segment Reporting Information, by Segment [Table Text Block] Income Statement [Abstract] Accumulated  Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Other Non-Current Liabilities Operating Lease, Liability, Noncurrent Amortization expense, year four Finite-Lived Intangible Asset, Expected Amortization, Year Four Prepaid expenses and other Increase (Decrease) in Prepaid Expense and Other Assets In-Process R&D Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Argil, Inc. Argil, Inc. [Member] Argil, Inc. CURRENT ASSETS Assets, Current [Abstract] CASH FLOWS (USED FOR) INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Market Value Investments, Fair Value Disclosure Dividends declared Dividends Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Gentex Patents Patents [Member] City Area Code City Area Code Document Period End Date Document Period End Date Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Aggregate Unrealized Losses, Total Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss Mexico MEXICO Operating lease, liability, current, statement of financial position Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Total net reclassifications for the period Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] INCOME BEFORE PROVISION FOR INCOME TAXES Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Amounts reclassified from accumulated other comprehensive income Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Current liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Schedule of Inventories Schedule of Inventory, Current [Table Text Block] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock Share-based Payment Arrangement, Noncash Expense Repurchases of common stock Stock Repurchased During Period, Value Plant and equipment additions Payments to Acquire Productive Assets Cover [Abstract] Acquisitions Goodwill, Acquired During Period Net decrease in period (in shares) NetDecreaseinCommonStockSharesfromSharesIssuedinShareBasedCompensationandSharesRepurchased Other Comprehensive income (loss) before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Fixed Income Securities Fixed Income Securities [Member] Long-term debt Long-term Debt Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Leases Lessee, Operating Leases [Text Block] Number of plans SharebasedCompensationArrangementbySharebasedPaymentAwardNumberOfPlans HomeLink® HomeLinkMember Employee Stock Purchase Plan EmployeeStockPurchasePlanMember Windows Products WindowsProductsMember Loss on disposal of assets Loss on Disposition of Assets Loss on Disposition of Assets COST OF GOODS SOLD Cost of Goods and Services Sold Total Debt Securities, Available-for-sale Equity Components [Axis] Equity Components [Axis] Automotive Segment AutomotiveSegmentMember Share-based Payment Arrangement [Abstract] Minimum Minimum [Member] Total assets acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Accrued Liabilities Operating Lease, Liability, Current Current Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets Weighted-Average Assumptions For The Employee Stock Option Plan Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Asset Backed Securities Asset-backed Securities [Member] Amortization expense Restricted Stock or Unit Expense Entity Interactive Data Current Entity Interactive Data Current U.S. UNITED STATES Corporate Bonds Corporate Bond Securities [Member] Investments Fair Value Disclosures [Text Block] CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Equity Stockholders' Equity Note Disclosure [Text Block] Maturities and calls Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Amortization expense, remainder of fiscal year Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year Additional paid-in capital Additional Paid in Capital, Common Stock Entity Registrant Name Entity Registrant Name Business Acquisition [Line Items] Business Acquisition [Line Items] Statement of Stockholders' Equity [Abstract] Weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Proceeds from sale of plant and equipment Proceeds from Sale of Property, Plant, and Equipment Intangible assets, gross Intangible Assets, Gross (Excluding Goodwill) Cash dividends paid Payments of Ordinary Dividends, Common Stock (Gain) on sale of investments Gain on Sale of Investments Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Investments [Abstract] Impairments Goodwill, Impairment Loss Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current Finished goods Inventory, Finished Goods, Gross Total future minimum lease payments Lessee, Operating Lease, Liability, to be Paid Unrealized Losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Remaining lease terms Lessee, Operating Lease, Remaining Lease Term Entity Address, Postal Zip Code Entity Address, Postal Zip Code Goodwill Balance as of December 31, 2020 Balance as of March 31, 2021 Goodwill Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Due within one year Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Document Transition Report Document Transition Report Aggregate Unrealized Losses, Loss duration greater than one year Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Acquisition-related costs Business Acquisition, Transaction Costs Cash Dividends Declared per Share (in dollars per share) Dividends declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Principal amount Debt Instrument, Face Amount Realized gain on sale of securities Equity Securities, FV-NI, Realized Gain (Loss) Level 2 Fair Value, Inputs, Level 2 [Member] Document Quarterly Report Document Quarterly Report Schedule of Goodwill Schedule of Goodwill [Table Text Block] Equity [Abstract] Total Assets, Fair Value Disclosure Other comprehensive income (loss), before tax Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent Schedule of Intangible Assets Schedule of Intangible Assets and Goodwill [Table Text Block] Diluted weighted average shares outstanding Weighted Average Number of Shares Outstanding, Diluted Letter of Credit Letter of Credit [Member] Basic (in dollars per share) Net (Loss) Income per share - Basic (in dollars per share) Earnings Per Share, Basic Expected term of options Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Entity File Number Entity File Number Debt Disclosure [Abstract] Weighted average remaining lease term Operating Lease, Weighted Average Remaining Lease Term Restricted Stock Plan RestrictedStockPlanMember Adjustments to reconcile net income to net cash provided by operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net cash (used for) financing activities Net Cash Provided by (Used in) Financing Activities Compensation expense for share-based payments Share-based Payment Arrangement, Expense Unrealized gains (losses) on available-for-sale debt securities AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] Common stock Common Stock, Value, Issued Long-term investments Long-term Investments Goodwill and Intangible Assets Disclosure [Abstract] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Document Fiscal Year Focus Document Fiscal Year Focus Amortization expense, year two Finite-Lived Intangible Asset, Expected Amortization, Year Two OTHER ASSETS Assets, Noncurrent [Abstract] Current portion of long-term debt Long-term Debt, Current Maturities Entity Current Reporting Status Entity Current Reporting Status Purchases Payments to Acquire Debt Securities, Available-for-sale Common stock issued under stock compensation plan (in shares) Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Inventory Disclosure [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Total Operating Lease, Liability Segment Reporting [Abstract] Accounts receivable, net Increase (Decrease) in Accounts Receivable Debt Instrument [Line Items] Debt Instrument [Line Items] Statement of Comprehensive Income [Abstract] Total shareholders’ investment Balance at beginning of period Balance at end of period Stockholders' Equity Attributable to Parent Purchase price of acquisition Business Combination, Consideration Transferred Total liabilities and shareholders’ investment Liabilities and Equity Accumulated other comprehensive income (loss) Accumulated other comprehensive income (loss), end of period Accumulated Other Comprehensive Income (Loss), Net of Tax Income Taxes Income Tax Disclosure [Text Block] Raw materials Inventory, Raw Materials, Gross Entity Address, City or Town Entity Address, City or Town Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Net Assets Acquired Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Total Liabilities assumed Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Financial Instrument [Axis] Financial Instrument [Axis] Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Less: Dividends and undistributed earnings allocated to participating securities Participating Securities, Distributed and Undistributed Earnings (Loss), Basic Indefinite-lived Intangible Assets by Major Class [Axis] Indefinite-lived Intangible Assets [Axis] Other comprehensive income (loss) before tax: Other Comprehensive Income (Loss), before Tax [Abstract] Finite-lived intangible asset, useful life Finite-Lived Intangible Asset, Useful Life Equity Component [Domain] Equity Component [Domain] Reclassification Out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Gross profit Gross Profit PLANT AND EQUIPMENT—NET Property, Plant and Equipment, Net Amortization expense, year three Finite-Lived Intangible Asset, Expected Amortization, Year Three Entity Tax Identification Number Entity Tax Identification Number Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Stock-Based Compensation Plans Share-based Payment Arrangement [Text Block] NET INCOME Net income Net income Net Income (Loss) Attributable to Parent Automotive Mirrors & Electronics AutomotiveMirrorsElectronicsMember Air-CraftGlass Air-CraftGlass [Member] Air-CraftGlass 2021 (excluding the three months ended March 31, 2021) Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year Change in operating assets and liabilities: Increase (Decrease) in Operating Assets [Abstract] Investment, Name [Domain] Investment, Name [Domain] Inventories Inventory Disclosure [Text Block] Other comprehensive (loss) income Other Comprehensive Income (Loss), Net of Tax Work-in-process Inventory, Work in Process, Gross Leases [Abstract] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Total current assets Assets, Current Current Fiscal Year End Date Current Fiscal Year End Date OPERATING EXPENSES: Operating Expenses [Abstract] EARNINGS PER SHARE: Earnings Per Share [Abstract] SHAREHOLDERS’ INVESTMENT Stockholders' Equity Attributable to Parent [Abstract] Accumulated other comprehensive income (loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] HomeLink® Technology Developed Technology Rights [Member] Document Fiscal Period Focus Document Fiscal Period Focus Loss on sale of investments Loss on Sale of Investments Certificate of Deposit Certificates of Deposit [Member] Net Income available to common shareholders - Diluted Net Income (Loss) Available to Common Stockholders, Diluted Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Long-Term Investments Other Long-term Investments [Member] Entity Filer Category Entity Filer Category Common Stock Common Stock [Member] Product and Service [Domain] Product and Service [Domain] Foreign currency translation adjustments Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Other OtherCountriesMember Existing Customer Platforms Customer Contracts [Member] Reclassifications Out of Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Vaporsens Technology Licenses Technology-Based Intangible Assets [Member] Additional borrowings available Debt Instrument Additional Borrowings Available Face Amount Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Government Securities US Treasury Securities [Member] Fire Protection Products FireProtectionProductsMember Shares approved Employee Stock Ownership Plan (ESOP), Shares in ESOP Issuance of common stock from stock plan transactions (in shares) Stock Issued During Period, Shares, New Issues Income tax impact related to components of other comprehensive income (loss) Other Comprehensive Income (Loss), Tax Finite-lived intangible assets, gross Finite-Lived Intangible Assets, Gross Aggregate Unrealized Losses, Loss duration less than one year Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Municipal Bonds Municipal Bonds [Member] Equity Incentive Plans Share-based Payment Arrangement [Member] Net Income available to common shareholders Allocation of Net Income used in basic computation Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic Earnings Per Share, Diluted [Abstract] Earnings Per Share, Diluted [Abstract] NET INCREASE IN CASH AND CASH EQUIVALENTS Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Acquisitions Business Combination Disclosure [Text Block] Total other income Nonoperating Income (Expense) Unrealized (losses) gains on debt securities, net OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment and Tax Future Minimum Lease Payments Lessee, Operating Lease, Liability, Maturity [Table Text Block] Cost Debt Securities, Available-for-sale, Amortized Cost, Current Basic weighted average shares outstanding Number of shares used in basic computation Weighted Average Number of Shares Outstanding, Basic Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Aggregate Fair Value of Investments, Loss duration less than one year Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value Equity investment losses were considered to be other than temporary Other than Temporary Impairment Losses, Investments Plan Name [Domain] Plan Name [Domain] Revenue Revenue from Contract with Customer [Text Block] Technology investments Equity Securities without Readily Determinable Fair Value, Amount Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Amortization expense, year one Finite-Lived Intangible Asset, Expected Amortization, Year One PROVISION FOR INCOME TAXES Provision for income taxes Income Tax Expense (Benefit) Reallocation of undistributed earnings Participating Securities, Distributed and Undistributed Earnings (Loss), Diluted CASH AND CASH EQUIVALENTS, beginning of period CASH AND CASH EQUIVALENTS, end of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Accrued liabilities Accrued Liabilities, Current Diluted (in dollars per share) Net Income per share - Diluted (in dollars per share) Earnings Per Share, Diluted Shares granted (in shares) Employee Stock Ownership Plan (ESOP), Number of Allocated Shares Sales proceeds Proceeds from Sale of Debt Securities, Available-for-sale Local Phone Number Local Phone Number (Gain) on disposal of assets Gain on Disposal of Assets Gain on Disposal of Assets Personal Property Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Equipment Entity Address, Address Line One Entity Address, Address Line One Increase in other assets Increase (Decrease) in Other Operating Assets Entity Emerging Growth Company Entity Emerging Growth Company Indefinite-lived intangible assets Indefinite-lived Intangible Assets (Excluding Goodwill) Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Change in deferred income taxes Deferred Income Tax Expense (Benefit) Award Type [Axis] Award Type [Axis] Finite-lived intangible assets, accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Maximum Maximum [Member] Dividends declared Dividends, Common Stock, Cash ESPP discount rate recognized as compensation expense Share-Based Compensation Arrangement By Share Based Payment Award, Discount Recognized As Compensation Expense Retained  Earnings Retained Earnings [Member] Divestitures Goodwill, Written off Related to Sale of Business Unit Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Net cash (used for) investing activities Net Cash Provided by (Used in) Investing Activities Option expiration period Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Domain] Award Type [Domain] Investments [Domain] Investments [Domain] Trading Symbol Trading Symbol Other Goodwill, Other Increase (Decrease) Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Earnings Per Share Earnings Per Share [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] CURRENT LIABILITIES Liabilities, Current [Abstract] CASH FLOWS (USED FOR) FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Entity Shell Company Entity Shell Company Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Schedule of Unrealized Loss on Investments Schedule of Unrealized Loss on Investments [Table Text Block] Statement of Financial Position [Abstract] Basic Earnings Per Share Earnings Per Share, Basic [Abstract] Short-term investments Short-term Investments