$GNTX
GENTEX CORP Stock $gntx

$gntx Overview Financials Valuation SEC Filings Company Website

2018 Q4 Form 10-K Financial Statement

#000035581120000007 Filed on February 26, 2020

Income Statement

Concept	2018 Q4	2018 Q3	2018 Q2
Revenue	$453.4M	$460.3M	$455.0M
YoY Change	-1.34%	4.93%	2.67%
Cost Of Revenue	$281.4M	$287.3M	$282.2M
YoY Change	0.75%	7.43%	2.26%
Gross Profit	$172.0M	$173.0M	$172.8M
YoY Change	-4.57%	1.03%	3.35%
Gross Profit Margin	37.94%	37.59%	37.98%
Selling, General & Admin	$19.50M	$18.67M	$18.92M
YoY Change	-10.14%	7.4%	17.52%
% of Gross Profit	11.33%	10.79%	10.95%
Research & Development	$27.00M	$26.89M	$27.20M
YoY Change	9.76%	8.55%	7.75%
% of Gross Profit	15.69%	15.54%	15.74%
Depreciation & Amortization	$21.50M	$24.80M	$27.90M
YoY Change	-12.96%	1.22%	10.71%
% of Gross Profit	12.5%	14.34%	16.15%
Operating Expenses	$46.50M	$45.56M	$46.12M
YoY Change	0.43%	8.08%	11.56%
Operating Profit	$125.5M	$127.4M	$126.7M
YoY Change	-6.34%	-1.27%	0.65%
Interest Expense	$3.200M	$3.100M	$2.500M
YoY Change	-5.88%	121.43%	150.0%
% of Operating Profit	2.55%	2.43%	1.97%
Other Income/Expense, Net	$2.100M	$3.107M	$2.290M
YoY Change	162.5%	76.58%	10.13%
Pretax Income	$130.8M	$130.5M	$129.0M
YoY Change	-5.35%	-0.23%	0.8%
Income Tax	$24.50M	$19.20M	$19.95M
% Of Pretax Income	18.73%	14.71%	15.47%
Net Earnings	$106.3M	$111.3M	$109.0M
YoY Change	-18.54%	23.39%	23.14%
Net Earnings / Revenue	23.44%	24.19%	23.96%
Basic Earnings Per Share	$0.41	$0.42	$0.40
Diluted Earnings Per Share	$0.41	$0.42	$0.40
COMMON SHARES
Basic Shares Outstanding	262.1M shares	265.6M shares	271.7M shares
Diluted Shares Outstanding		267.6M shares	274.1M shares

Balance Sheet

Concept	2018 Q4	2018 Q3	2018 Q2
SHORT-TERM ASSETS
Cash & Short-Term Investments	$386.4M	$337.6M	$467.7M
YoY Change	-46.5%	-54.42%	-38.87%
Cash & Equivalents	$217.0M	$194.0M	$296.7M
Short-Term Investments	$169.4M	$143.6M	$171.0M
Other Short-Term Assets	$25.70M	$29.20M	$23.60M
YoY Change	78.47%	82.5%	71.01%
Inventory	$225.3M	$213.4M	$212.4M
Prepaid Expenses
Receivables	$213.5M	$247.3M	$239.4M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$850.9M	$827.6M	$943.1M
YoY Change	-28.17%	-31.26%	-21.72%
LONG-TERM ASSETS
Property, Plant & Equipment	$498.5M	$497.3M	$499.7M
YoY Change	1.22%	0.74%	3.54%
Goodwill	$307.4M	$307.4M	$307.4M
YoY Change	0.0%	0.0%	0.0%
Intangibles	$269.7M	$274.5M	$279.3M
YoY Change	-6.68%	-6.57%	-6.46%
Long-Term Investments	$138.0M	$141.6M	$141.3M
YoY Change	138.75%	173.89%	186.61%
Other Assets	$736.0M	$744.5M	$749.4M
YoY Change	9.04%	10.45%	10.72%
Total Long-Term Assets	$1.235B	$1.242B	$1.249B
YoY Change	5.74%	6.34%	7.73%
TOTAL ASSETS
Total Short-Term Assets	$850.9M	$827.6M	$943.1M
Total Long-Term Assets	$1.235B	$1.242B	$1.249B
Total Assets	$2.085B	$2.069B	$2.192B
YoY Change	-11.34%	-12.74%	-7.27%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$92.81M	$90.04M	$106.8M
YoY Change	3.24%	12.69%	28.78%
Accrued Expenses	$76.35M	$82.84M	$84.53M
YoY Change	0.79%	-55.22%	-55.09%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$23.10M
YoY Change
Long-Term Debt Due	$0.00	$0.00	$23.13M
YoY Change	-100.0%
Total Short-Term Liabilities	$169.2M	$172.9M	$214.4M
YoY Change	-30.57%	-34.74%	-20.91%
LONG-TERM LIABILITIES
Long-Term Debt	$0.00	$0.00	$0.00
YoY Change			-100.0%
Other Long-Term Liabilities	$0.00
YoY Change
Total Long-Term Liabilities	$0.00	$0.00	$0.00
YoY Change			-100.0%
TOTAL LIABILITIES
Total Short-Term Liabilities	$169.2M	$172.9M	$214.4M
Total Long-Term Liabilities	$0.00	$0.00	$0.00
Total Liabilities	$223.7M	$226.3M	$270.6M
YoY Change	-26.06%	-34.48%	-24.86%
SHAREHOLDERS EQUITY
Retained Earnings	$1.102B	$1.086B	$1.157B
YoY Change	-15.32%	-15.79%	-9.39%
Common Stock	$760.9M	$759.2M	$764.9M
YoY Change	2.78%	3.91%	5.67%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$1.862B	$1.843B	$1.921B
YoY Change
Total Liabilities & Shareholders Equity	$2.085B	$2.069B	$2.192B
YoY Change	-11.34%	-12.74%	-7.27%

Cashflow Statement

Concept	2018 Q4	2018 Q3	2018 Q2
OPERATING ACTIVITIES
Net Income	$106.3M	$111.3M	$109.0M
YoY Change	-18.54%	23.39%	23.14%
Depreciation, Depletion And Amortization	$21.50M	$24.80M	$27.90M
YoY Change	-12.96%	1.22%	10.71%
Cash From Operating Activities	$154.2M	$105.8M	$145.0M
YoY Change	3.91%	18.88%	9.52%
INVESTING ACTIVITIES
Capital Expenditures	-$18.30M	-$18.50M	-$28.60M
YoY Change	2.23%	-38.13%	0.35%
Acquisitions
YoY Change
Other Investing Activities	-$19.70M	$26.90M	-$157.1M
YoY Change	-195.17%	301.49%	-2140.26%
Cash From Investing Activities	-$38.00M	$8.400M	-$185.7M
YoY Change	-1410.34%	-136.05%	792.79%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-93.20M	-216.9M	-186.9M
YoY Change	-35.05%	157.3%	106.06%
NET CHANGE
Cash From Operating Activities	154.2M	105.8M	145.0M
Cash From Investing Activities	-38.00M	8.400M	-185.7M
Cash From Financing Activities	-93.20M	-216.9M	-186.9M
Net Change In Cash	23.00M	-102.7M	-227.6M
YoY Change	194.87%	452.15%	-1189.0%
FREE CASH FLOW
Cash From Operating Activities	$154.2M	$105.8M	$145.0M
Capital Expenditures	-$18.30M	-$18.50M	-$28.60M
Free Cash Flow	$172.5M	$124.3M	$173.6M
YoY Change	3.73%	4.54%	7.89%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2019	dei	Amendment Flag AmendmentFlag	false
CY2019	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2019	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2019	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2019
CY2019	dei	Entity Central Index Key EntityCentralIndexKey	0000355811
CY2018Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.06
CY2019Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.06
CY2018Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	400000000	shares
CY2019Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	400000000	shares
CY2018Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	259328613	shares
CY2019Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	251277515	shares
CY2018Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	259328613	shares
CY2019Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	251277515	shares
CY2018Q4	us-gaap	Goodwill Goodwill	307400000	USD
CY2018	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2017	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P2Y
CY2018	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P1Y8M12D
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P2Y2M12D
CY2017	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P2Y8M12D
CY2018	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P2Y9M18D
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P3Y1M6D
CY2019	dei	Document Type DocumentType	10-K
CY2019	dei	Document Annual Report DocumentAnnualReport	true
CY2019	dei	Document Period End Date DocumentPeriodEndDate	2019-12-31
CY2019	dei	Document Transition Report DocumentTransitionReport	false
CY2019	dei	Entity File Number EntityFileNumber	000-10235
CY2019	dei	Entity Registrant Name EntityRegistrantName	GENTEX CORPORATION
CY2019	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	MI
CY2019	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	38-2030505
CY2019	dei	Entity Address Address Line1 EntityAddressAddressLine1	600 N. Centennial Street,
CY2019	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	49464
CY2019	dei	Entity Address City Or Town EntityAddressCityOrTown	Zeeland,
CY2019	dei	Entity Address State Or Province EntityAddressStateOrProvince	MI
CY2019	dei	Trading Symbol TradingSymbol	GNTX
CY2019	dei	Security Exchange Name SecurityExchangeName	NASDAQ
CY2019	dei	City Area Code CityAreaCode	616
CY2019	dei	Local Phone Number LocalPhoneNumber	772-1800
CY2019	dei	Security12b Title Security12bTitle	Common Stock, par value $.06 per share
CY2019Q4	us-gaap	Assets Assets	2168803193	USD
CY2018Q4	us-gaap	Assets Assets	2085434068	USD
CY2019Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	97553917	USD
CY2018Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	92810316	USD
CY2019	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2019	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2019	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2019	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2019	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2019	dei	Entity Small Business EntitySmallBusiness	false
CY2019	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2019	dei	Entity Shell Company EntityShellCompany	false
CY2019Q2	dei	Entity Public Float EntityPublicFloat	6258471128	USD
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CY2019Q4	us-gaap	Buildings And Improvements Gross BuildingsAndImprovementsGross	344231180	USD
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CY2018Q4	us-gaap	Construction In Progress Gross ConstructionInProgressGross	18156423	USD
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CY2018Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	1197953787	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	728811261	USD
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CY2019Q4	us-gaap	Goodwill Goodwill	307365845	USD
CY2018Q4	us-gaap	Goodwill Goodwill	307365845	USD
CY2019Q4	us-gaap	Long Term Investments LongTermInvestments	139909323	USD
CY2018Q4	us-gaap	Long Term Investments LongTermInvestments	137979082	USD
CY2019Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	250375000	USD
CY2018Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	269675000	USD
CY2019Q4	gntx	Patentand Other Assets Net PatentandOtherAssetsNet	22460033	USD
CY2018Q4	gntx	Patentand Other Assets Net PatentandOtherAssetsNet	21010121	USD
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CY2019Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	16385833	USD
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CY2019	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	-709702	USD
CY2018	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	-2319917	USD
CY2017	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	3508029	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	98767	USD
CY2017	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	1721933	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	1292325	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	115059	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	5903699	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	582623	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	-2106091	USD
CY2017	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	11133661	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	271388	USD
CY2018	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	44903	USD
CY2017	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	2668973	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	311235	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-2150994	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	8464688	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	424995174	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	435732103	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	415256610	USD
CY2016Q4	us-gaap	Stockholders Equity StockholdersEquity	1910424234	USD
CY2017	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	47770467	USD
CY2017	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	231363216	USD
CY2017	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	18376965	USD
CY2017	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	110946799	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	406791922	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	8464688	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	2049518261	USD
CY2018	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	66837820	USD
CY2018	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	591577851	USD
CY2018	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	18305981	USD
CY2018	us-gaap	New Accounting Pronouncement Or Change In Accounting Principle Effect Of Adoption Quantification NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification	0	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	117064654	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	437883097	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-2150994	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	1861751660	USD
CY2019	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	77821151	USD
CY2019	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	331471392	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	21671192	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	116679965	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	424683939	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	311235	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	1938087820	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	424683939	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	437883097	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	406791922	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	104702974	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	102186814	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	99570908	USD
CY2019	gntx	Gain On Disposition On Assets GainOnDispositionOnAssets	155150	USD
CY2018	gntx	Gain On Disposition On Assets GainOnDispositionOnAssets	577200	USD
CY2017	gntx	Gain On Disposition On Assets GainOnDispositionOnAssets	188150	USD
CY2019	gntx	Loss On Disposition Of Assets LossOnDispositionOfAssets	588941	USD
CY2018	gntx	Loss On Disposition Of Assets LossOnDispositionOfAssets	108927	USD
CY2017	gntx	Loss On Disposition Of Assets LossOnDispositionOfAssets	299174	USD
CY2019	us-gaap	Gain On Sale Of Investments GainOnSaleOfInvestments	660643	USD
CY2018	us-gaap	Gain On Sale Of Investments GainOnSaleOfInvestments	2538729	USD
CY2017	us-gaap	Gain On Sale Of Investments GainOnSaleOfInvestments	1309166	USD
CY2019	us-gaap	Loss On Sale Of Investments LossOnSaleOfInvestments	176360	USD
CY2018	us-gaap	Loss On Sale Of Investments LossOnSaleOfInvestments	532494	USD
CY2017	us-gaap	Loss On Sale Of Investments LossOnSaleOfInvestments	375388	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-3358537	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-4414739	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-14996179	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	21671192	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	18305981	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	18376965	USD
CY2019	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	21872527	USD
CY2018	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-17583989	USD
CY2017	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	19530043	USD
CY2019	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	23660256	USD
CY2018	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	8516016	USD
CY2017	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	27454146	USD
CY2019	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	3646457	USD
CY2018	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	11268677	USD
CY2017	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	-16183673	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	4743601	USD
CY2018	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	2911849	USD
CY2017	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	9934837	USD
CY2019	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	2753427	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	552418646	USD
CY2018	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	220856	USD
CY2017	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	12947597	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	505966864	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	501002780	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	57139135	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	55248551	USD
CY2017	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	30207523	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	125013589	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	181892136	USD
CY2017	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	23100000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	153257603	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	332106362	USD
CY2017	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	29874960	USD
CY2019	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	84580255	USD
CY2018	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	85990570	USD
CY2017	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	104040919	USD
CY2019	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	2001315	USD
CY2018	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	738093	USD
CY2017	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	249757	USD
CY2019	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	3027263	USD
CY2018	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	5603042	USD
CY2017	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-2646029	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-56711082	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-185821194	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-77712570	USD
CY2019	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	0	USD
CY2018	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	78000000	USD
CY2017	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	107625000	USD
CY2019	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	77821151	USD
CY2018	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	66837820	USD
CY2017	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	47770467	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	116309197	USD
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	116566639	USD
CY2017	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	108815040	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	331471392	USD
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	591577851	USD
CY2017	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	231363216	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-369959438	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-719306670	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-400032789	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	79296344	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-352709218	USD
CY2017	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	23257421	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	217025278	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	569734496	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	546477075	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	271275758	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	303467531	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	440807	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	296321622	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	217025278	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	569734496	USD
CY2019Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	9000000.0	USD
CY2018Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	3900000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	296321622	USD
CY2019Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	567597380	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	217025278	USD
CY2018Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	520567359	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	269889067	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	1974255	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	587564	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	366257	USD
CY2018Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	303542081	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	587564	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	90721081	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	0	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	0	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	587564	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	90721081	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	365824	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	68722980	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	433	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	3000000	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	366257	USD
CY2018Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	71722980	USD
CY2019	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2019Q4	us-gaap	Inventory Finished Goods InventoryFinishedGoods	50898047	USD
CY2018Q4	us-gaap	Inventory Finished Goods InventoryFinishedGoods	50836443	USD
CY2019Q4	us-gaap	Inventory Raw Materials InventoryRawMaterials	164974553	USD
CY2018Q4	us-gaap	Inventory Raw Materials InventoryRawMaterials	139058541	USD
CY2019Q4	us-gaap	Inventory Work In Process InventoryWorkInProcess	33069255	USD
CY2018Q4	us-gaap	Inventory Work In Process InventoryWorkInProcess	35386615	USD
CY2019Q4	us-gaap	Inventory Net InventoryNet	248941855	USD
CY2018Q4	us-gaap	Inventory Net InventoryNet	225281599	USD
CY2019	gntx	Allowance For Obsolete And Slow Moving Inventories AllowanceForObsoleteAndSlowMovingInventories	7600000	USD
CY2018	gntx	Allowance For Obsolete And Slow Moving Inventories AllowanceForObsoleteAndSlowMovingInventories	7800000	USD
CY2019	us-gaap	Depreciation Depreciation	82300000	USD
CY2018	us-gaap	Depreciation Depreciation	79700000	USD
CY2017	us-gaap	Depreciation Depreciation	77000000.0	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	437883097	USD
CY2019	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	3000000.0	USD
CY2018	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	2500000	USD
CY2017	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	2600000	USD
CY2019	us-gaap	Cost Of Property Repairs And Maintenance CostOfPropertyRepairsAndMaintenance	28900000	USD
CY2018	us-gaap	Cost Of Property Repairs And Maintenance CostOfPropertyRepairsAndMaintenance	28900000	USD
CY2017	us-gaap	Cost Of Property Repairs And Maintenance CostOfPropertyRepairsAndMaintenance	24600000	USD
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P2Y
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.029
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	786807	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	297316	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	145154	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	19296	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	15105	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	1263678	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	84964	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	1178714	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	424683939	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	406791922	USD
CY2019	us-gaap	Participating Securities Distributed And Undistributed Earnings Loss Basic ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic	5028813	USD
CY2019	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	419655126	USD
CY2018	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	437883097	USD
CY2017	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	406791922	USD
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	251766382	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	267794786	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	285864997	shares
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.67
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.64
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.42
CY2019	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	419655126	USD
CY2018	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	437883097	USD
CY2017	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	406791922	USD
CY2019	us-gaap	Participating Securities Distributed And Undistributed Earnings Loss Diluted ParticipatingSecuritiesDistributedAndUndistributedEarningsLossDiluted	-21104	USD
CY2018	us-gaap	Participating Securities Distributed And Undistributed Earnings Loss Diluted ParticipatingSecuritiesDistributedAndUndistributedEarningsLossDiluted	-21007	USD
CY2017	us-gaap	Participating Securities Distributed And Undistributed Earnings Loss Diluted ParticipatingSecuritiesDistributedAndUndistributedEarningsLossDiluted	-19398	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	419676230	USD
CY2018	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	437904104	USD
CY2017	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	406811320	USD
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	251766382	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	267794786	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	285864997	shares
CY2019	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	1506608	shares
CY2018	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	2082563	shares
CY2017	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	2361092	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	253272990	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	269877349	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	288226089	shares
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.66
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.62
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.41
CY2018	us-gaap	Participating Securities Distributed And Undistributed Earnings Loss Basic ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic	3836536	USD
CY2017	us-gaap	Participating Securities Distributed And Undistributed Earnings Loss Basic ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic	2562473	USD
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	247855	shares
CY2018	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	698019	shares
CY2017	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	910105	shares
CY2017	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.005
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Deductions Qualified Production Activities EffectiveIncomeTaxRateReconciliationDeductionsQualifiedProductionActivities	0
CY2019	us-gaap	Use Of Estimates UseOfEstimates	<div style="line-height:120%;padding-top:10px;text-align:justify;font-size:10pt;"><span style="font-family:Arial;font-size:10pt;text-decoration:underline;">Estimates</span></div><div style="line-height:120%;padding-top:10px;text-align:justify;font-size:10pt;"><span style="font-family:Arial;font-size:10pt;">The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.</span></div>
CY2017	gntx	Tax Cutsand Jobs Actof2017 Incomplete Accounting Changein Tax Rate Deferred Tax Liability Provisional Income Tax Expense Benefit TaxCutsandJobsActof2017IncompleteAccountingChangeinTaxRateDeferredTaxLiabilityProvisionalIncomeTaxExpenseBenefit	38400000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Deductions Qualified Production Activities EffectiveIncomeTaxRateReconciliationDeductionsQualifiedProductionActivities	0
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	73563685	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	83010387	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	133166194	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	3765929	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	3743781	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	3984000	USD
CY2019	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	1468018	USD
CY2018	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	1776837	USD
CY2017	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	2440000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	78797632	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	88531005	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	139590194	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-3066237	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-4367155	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-14585412	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	75731395	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	84163850	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	125004782	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.350
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.006
CY2018	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.006
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Deductions Qualified Production Activities EffectiveIncomeTaxRateReconciliationDeductionsQualifiedProductionActivities	0.028
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Research EffectiveIncomeTaxRateReconciliationTaxCreditsResearch	0.011
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Research EffectiveIncomeTaxRateReconciliationTaxCreditsResearch	0.008
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Research EffectiveIncomeTaxRateReconciliationTaxCreditsResearch	0.008
CY2019	gntx	Effective Income Tax Rate Reconciliation Increase Reductionin Reservefor Uncertain Tax Provisions EffectiveIncomeTaxRateReconciliationIncreaseReductioninReserveforUncertainTaxProvisions	0.003
CY2018	gntx	Effective Income Tax Rate Reconciliation Increase Reductionin Reservefor Uncertain Tax Provisions EffectiveIncomeTaxRateReconciliationIncreaseReductioninReserveforUncertainTaxProvisions	0.001
CY2017	gntx	Effective Income Tax Rate Reconciliation Increase Reductionin Reservefor Uncertain Tax Provisions EffectiveIncomeTaxRateReconciliationIncreaseReductioninReserveforUncertainTaxProvisions	0.001
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0.005
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	-0.072
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Foreign EffectiveIncomeTaxRateReconciliationTaxCreditsForeign	0.001
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Foreign EffectiveIncomeTaxRateReconciliationTaxCreditsForeign	0.001
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Foreign EffectiveIncomeTaxRateReconciliationTaxCreditsForeign	0.008
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Deductions Extraterritorial Income Exclusion EffectiveIncomeTaxRateReconciliationDeductionsExtraterritorialIncomeExclusion	0.048
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Deductions Extraterritorial Income Exclusion EffectiveIncomeTaxRateReconciliationDeductionsExtraterritorialIncomeExclusion	0.046
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Deductions Extraterritorial Income Exclusion EffectiveIncomeTaxRateReconciliationDeductionsExtraterritorialIncomeExclusion	0
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Percent EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent	0.011
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Percent EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent	0.010
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Percent EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitPercent	0.010
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.003
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.004
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.005
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.151
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.161
CY2017	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.235
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals	6478146	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals	5111242	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	9100745	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	9586372	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	66830	USD
CY2018Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	356039	USD
CY2019Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	15645721	USD
CY2018	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	0	USD
CY2017	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	140000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	6392000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	4678000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	15053653	USD
CY2019Q4	gntx	Deferred Tax Liabilities Deferred Expense Excess Tax Over Book Depreciation DeferredTaxLiabilitiesDeferredExpenseExcessTaxOverBookDepreciation	30725471	USD
CY2018Q4	gntx	Deferred Tax Liabilities Deferred Expense Excess Tax Over Book Depreciation DeferredTaxLiabilitiesDeferredExpenseExcessTaxOverBookDepreciation	39835025	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Patent Costs DeferredTaxLiabilitiesDeferredExpenseCapitalizedPatentCosts	27799640	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Patent Costs DeferredTaxLiabilitiesDeferredExpenseCapitalizedPatentCosts	23341226	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	6171628	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	5089042	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	2403131	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	1309849	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	67099870	USD
CY2018Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	69575142	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	51454149	USD
CY2018Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	54521489	USD
CY2019	us-gaap	Income Taxes Paid IncomeTaxesPaid	74900000	USD
CY2018	us-gaap	Income Taxes Paid IncomeTaxesPaid	86900000	USD
CY2017	us-gaap	Income Taxes Paid IncomeTaxesPaid	126000000.0	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	4678000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	4435000	USD
CY2016Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	3408000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	1695000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	1677000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	941000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	657000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	283000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	289000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	38000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	163000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	63000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	1554000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	600000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	4435000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	574000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	315000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	433000	USD
CY2019	us-gaap	Defined Benefit Plan Contributions By Employer DefinedBenefitPlanContributionsByEmployer	8700000	USD
CY2018	us-gaap	Defined Benefit Plan Contributions By Employer DefinedBenefitPlanContributionsByEmployer	8200000	USD
CY2017	us-gaap	Defined Benefit Plan Contributions By Employer DefinedBenefitPlanContributionsByEmployer	7700000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.020
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.021
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.021
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.239
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.260
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.267
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.018
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.027
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.020
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P4Y2M12D
CY2018	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P4Y2M12D
CY2017	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P4Y2M12D
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	4
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	5
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	4
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	8944000	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	18
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod	1049000	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	25
CY2019	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	4402000	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	16
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	36294000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	156000	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	20
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	1859000	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	18
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	5435000	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	20
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	47170000	USD
CY2019Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	20484000	USD
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	11837000	shares
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	16
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod	1613000	shares
CY2018	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	22
CY2018	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	4278000	shares
CY2018	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	15
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	38097000	USD
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	228000	shares
CY2018	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	18
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	8944000	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	18
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	24881000	USD
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	4101000	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	16
CY2018Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	16162000	USD
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	14252000	shares
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	15
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod	1295000	shares
CY2017	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	20
CY2017	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	3476000	shares
CY2017	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	13
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	25156000	USD
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	234000	shares
CY2017	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	16
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	11837000	shares
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	16
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	58202000	USD
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	5297000	shares
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	15
CY2017Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	32152000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1858897406	USD
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	4842000	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	4
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	6540000	shares
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	4
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	9397000	shares
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	4
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	1049000	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	4
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	1613000	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	5
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	1295000	shares
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	4
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	2165000	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	4
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	3089000	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	4
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	3941000	shares
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	4
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	151000	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	4
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	222000	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	4
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	211000	shares
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	4
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	3575000	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	4
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	4842000	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	4
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	6540000	shares
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	4
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1834063697	USD
CY2017	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1794872578	USD
CY2019	us-gaap	Operating Income Loss OperatingIncomeLoss	488537604	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	508125547	USD
CY2017	us-gaap	Operating Income Loss OperatingIncomeLoss	523358352	USD
CY2019Q4	us-gaap	Assets Assets	2168803193	USD
CY2018Q4	us-gaap	Assets Assets	2085434068	USD
CY2017Q4	us-gaap	Assets Assets	2352053912	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	99570908	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	104702974	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	102186814	USD
CY2017	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	104040919	USD
CY2019	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	84580255	USD
CY2018	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	85990570	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1858897406	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1834063697	USD
CY2017	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1794872578	USD
CY2019Q4	gntx	Percentage Net Sales Invoiced And Paid In Foreign Currencies PercentageNetSalesInvoicedAndPaidInForeignCurrencies	0.07
CY2018Q4	gntx	Percentage Net Sales Invoiced And Paid In Foreign Currencies PercentageNetSalesInvoicedAndPaidInForeignCurrencies	0.08
CY2017Q4	gntx	Percentage Net Sales Invoiced And Paid In Foreign Currencies PercentageNetSalesInvoicedAndPaidInForeignCurrencies	0.08
CY2019Q4	gntx	Number Of Customers Which Individually Accounted For10 Percent Or More Of Net Sales NumberOfCustomersWhichIndividuallyAccountedFor10PercentOrMoreOfNetSales	3	automotive_customer
CY2019Q1	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	468589000	USD
CY2018Q1	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	465420000	USD
CY2019Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	468711000	USD
CY2018Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	454981000	USD
CY2019Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	477761000	USD
CY2018Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	460253000	USD
CY2019Q4	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	443836000	USD
CY2018Q4	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	453409000	USD
CY2019Q1	us-gaap	Gross Profit GrossProfit	169645000	USD
CY2018Q1	us-gaap	Gross Profit GrossProfit	172628000	USD
CY2019Q2	us-gaap	Gross Profit GrossProfit	176538000	USD
CY2018Q2	us-gaap	Gross Profit GrossProfit	172804000	USD
CY2019Q3	us-gaap	Gross Profit GrossProfit	180321000	USD
CY2018Q3	us-gaap	Gross Profit GrossProfit	172990000	USD
CY2019Q4	us-gaap	Gross Profit GrossProfit	161805000	USD
CY2018Q4	us-gaap	Gross Profit GrossProfit	172044000	USD
CY2019Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	121596000	USD
CY2018Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	128515000	USD
CY2019Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	127905000	USD
CY2018Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	126683000	USD
CY2019Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	128136000	USD
CY2018Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	127428000	USD
CY2019Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	110901000	USD
CY2018Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	125499000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	104280000	USD
CY2018Q1	us-gaap	Net Income Loss NetIncomeLoss	111249000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	108959000	USD
CY2018Q2	us-gaap	Net Income Loss NetIncomeLoss	109024000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	111898000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	111336000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	99547000	USD
CY2018Q4	us-gaap	Net Income Loss NetIncomeLoss	106275000	USD
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.40
CY2018Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.40
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.42
CY2018Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.40
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.44
CY2018Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.42
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.39
CY2018Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.41
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.40
CY2018Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.40
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.42
CY2018Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.40
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.44
CY2018Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.42
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.39
CY2018Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.41
CY2019Q4	us-gaap	Goodwill Goodwill	307400000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	307365845	USD
CY2019	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	0	USD
CY2019	us-gaap	Goodwill Written Off Related To Sale Of Business Unit GoodwillWrittenOffRelatedToSaleOfBusinessUnit	0	USD
CY2019	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2019	us-gaap	Goodwill Other Increase Decrease GoodwillOtherIncreaseDecrease	0	USD
CY2019Q4	us-gaap	Goodwill Goodwill	307365845	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	22400000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	22500000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	22500000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1858897406	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1834063697	USD
CY2017	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1794872578	USD

Files In Submission

Name	View Source	Status
0000355811-20-000007-index-headers.html	Edgar Link	pending
0000355811-20-000007-index.html	Edgar Link	pending
0000355811-20-000007.txt	Edgar Link	pending
0000355811-20-000007-xbrl.zip	Edgar Link	pending
chart-3bc8d12b87d55c268d0.jpg	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
gntx-20191231.xsd	Edgar Link	pending
gntx-20191231_cal.xml	Edgar Link	unprocessable
gntx-20191231_def.xml	Edgar Link	unprocessable
gntx-20191231_lab.xml	Edgar Link	unprocessable
gntx-20191231_pre.xml	Edgar Link	unprocessable
gntx12312019-10k.htm	Edgar Link	pending
gntx12312019-10k_htm.xml	Edgar Link	completed
gntx12312019-ex21.htm	Edgar Link	pending
gntx12312019-ex231.htm	Edgar Link	pending
gntx12312019-ex311.htm	Edgar Link	pending
gntx12312019-ex312.htm	Edgar Link	pending
gntx12312019-ex32.htm	Edgar Link	pending
gntx12312019-ex42.htm	Edgar Link	pending
MetaLinks.json	Edgar Link	pending
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report.css	Edgar Link	pending
Show.js	Edgar Link	pending

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$GNTX
GENTEX CORP Stock $gntx

2018 Q4 Form 10-K Financial Statement

#000035581120000007 Filed on February 26, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$GNTX GENTEX CORP Stock $gntx

2018 Q4 Form 10-K Financial Statement

#000035581120000007 Filed on February 26, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$GNTX
GENTEX CORP Stock $gntx