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Goodwill and Other Intangible Assets (Details) - USD ($) | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | ---
Jun. 30, 2017 | Jun. 30, 2016 | Jun. 30, 2017 | Jun. 30, 2016 | Dec. 31, 2016 | Sep. 27, 2013
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |
Goodwill | $ 307,365,845 |  | $ 307,365,845 |  | $ 307,365,845 | [1] |
Amortization expense, 2017 | 22,000,000 |  | 22,000,000 |  |  |  |
Amortization expense, 2018 | 22,000,000 |  | 22,000,000 |  |  |  |
Amortization expense, 2019 | 22,000,000 |  | 22,000,000 |  |  |  |
Amortization expense, 2020 | 22,000,000 |  | 22,000,000 |  |  |  |
Amortization expense, 2021 | 22,000,000 |  | 22,000,000 |  |  |  |
HomeLink® |  |  |  |  |  |  |
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  | $ 307,400,000
Accumulated amortization | 72,375,000 |  | 72,375,000 |  | 62,725,000 |  |
Gentex Patents |  |  |  |  |  |  |
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |
Accumulated amortization | 17,473,999 |  | 17,473,999 |  | 16,481,728 |  |
Patents and Other Intangible Assets |  |  |  |  |  |  |
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |
Accumulated amortization | 89,848,999 |  | 89,848,999 |  | $ 79,206,728 |  |
Patents and Other Intangible Assets | HomeLink® |  |  |  |  |  |  |
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |
Amortization expense | $ 5,700,000 | $ 5,600,000 | $ 11,300,000 | $ 11,100,000 |  |  |
[1] | Note: The condensed consolidated balance sheet at December 31, 2016 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

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- Definition The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
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- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
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- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
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