XML 60 R50.htm IDEA: XBRL DOCUMENT
v3.19.2

Revenue (Details) - USD ($) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | $ 468,711,354 | $ 454,981,440 | $ 937,300,351 | $ 920,401,545
Automotive Segment |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 456,625,064 | 444,245,425 | 912,423,707 | 899,210,799
Other Segment |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 12,086,290 | 10,736,015 | 24,876,644 | 21,190,746
Automotive Products |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 456,625,064 | 444,245,425 | 912,423,707 | 899,210,799
Automotive Mirrors & Electronics | Automotive Segment |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 413,429,267 | 396,547,385 | 822,400,934 | 800,789,013
HomeLink Modules | Automotive Segment |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 43,195,797 | 47,698,040 | 90,022,773 | 98,421,786
Fire Protection Products | Other Segment |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 6,359,266 | 5,813,210 | 12,211,499 | 11,092,868
Windows Products | Other Segment |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 5,727,024 | 4,922,805 | 12,665,145 | 10,097,878
U.S. | Automotive Products |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 144,547,946 | 142,896,639 | 285,931,010 | 283,209,626
U.S. | Other Products |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 12,086,290 | 10,736,015 | 24,876,644 | 21,190,746
Germany | Automotive Products |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 73,151,692 | 85,642,205 | 151,601,619 | 177,435,746
Japan | Automotive Products |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 55,722,292 | 48,647,082 | 112,055,986 | 98,480,079
Mexico | Automotive Products |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 42,178,705 | 22,358,617 | 86,589,093 | 45,457,427
Other | Automotive Products |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | $ 141,024,429 | $ 144,700,882 | $ 276,245,999 | $ 294,627,921

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DisaggregationOfRevenueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045 + Details
Name: | us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=gntx_AutomotiveSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=gntx_OtherSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=gntx_AutomotiveProductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=gntx_AutomotiveMirrorsElectronicsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=gntx_HomeLinkModulesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=gntx_FireProtectionProductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=gntx_WindowsProductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_US
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=gntx_OtherProductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_DE
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_JP
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_MX
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=gntx_OtherCountriesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |