Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Jul. 22, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	GENTEX CORPORATION
Entity Central Index Key	0000355811
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q2
Amendment Flag	false
Trading Symbol	gntx
Entity Common Stock, Shares Outstanding		286,790,889