Document and Entity Information
Jan. 31, 2020
Cover page.  
Document Type 8-K
Document Period End Date Jan. 31, 2020
Entity Registrant Name GENTEX CORPORATION
Entity Central Index Key 0000355811
Amendment Flag false
Entity Incorporation, State or Country Code MI
Entity File Number 0-10235
Entity Tax Identification Number 38-2030505
Entity Address, Address Line One 600 North Centennial Street
Entity Address, City or Town Zeeland
Entity Address, State or Province MI
Entity Address, Postal Zip Code 49464
City Area Code 616
Local Phone Number 772-1800
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common Stock, par value $0.06 per share
Trading Symbol GNTX
Security Exchange Name NASDAQ
Entity Emerging Growth Company false