Gentex (GNTX) 10-Q 5 Nov 15 2015 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 22, 2015
Document And Entity Information [Abstract]
Entity Registrant Name	GENTEX CORPORATION
Entity Central Index Key	355,811
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Trading Symbol	gntx
Entity Common Stock, Shares Outstanding		291,524,142

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Balance Sheets - USD ($)	Sep. 30, 2015	Dec. 31, 2014
CURRENT ASSETS
Cash and cash equivalents	$ 564,528,197	$ 497,429,804	[1]
Accounts receivable, net	208,203,616	168,008,704	[1]
Inventories	164,604,063	141,757,884	[1]
Prepaid expenses and other	41,867,345	49,441,302	[1]
Total current assets	979,203,221	856,637,694	[1]
PLANT AND EQUIPMENT—NET	388,188,954	373,390,992	[1]
OTHER ASSETS
Goodwill	307,365,845	307,365,845	[1]
Long-term investments	94,424,586	114,642,567	[1]
Intangible Assets, net	332,400,000	346,875,000	[1]
Patents and other assets, net	22,428,765	23,627,931	[1]
Total other assets	756,619,196	792,511,343	[1]
Total assets	2,124,011,371	2,022,540,029	[1]
CURRENT LIABILITIES
Accounts payable	83,892,258	71,456,983	[1]
Accrued liabilities	97,737,628	61,974,180
Total current liabilities	181,629,886	133,431,163	[1]
LONG TERM DEBT	227,500,000	258,125,000
DEFERRED INCOME TAXES	43,785,884	59,571,421	[1]
TOTAL LIABILITIES	452,915,770	451,127,584	[1]
SHAREHOLDERS’ INVESTMENT
Common stock	17,534,331	17,714,877	[1]
Additional paid-in capital	584,423,871	553,836,483	[1]
Retained earnings	1,070,899,025	988,548,070	[1]
Accumulated other comprehensive income	(1,761,626)	11,313,015	[1]
Total shareholders’ investment	1,671,095,601	1,571,412,445	[1]
Total liabilities and shareholders’ investment	$ 2,124,011,371	$ 2,022,540,029	[1]
[1]	Note: The condensed consolidated balance sheet at December 31, 2014 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.

Unaudited Condensed Consolidat3

Unaudited Condensed Consolidated Statements of Income - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
NET SALES	$ 389,829,139	$ 350,913,912	$ 1,138,025,071	$ 1,025,090,220
COST OF GOODS SOLD	237,932,439	212,288,220	697,492,531	620,873,493
Gross profit	151,896,700	138,625,692	440,532,540	404,216,727
OPERATING EXPENSES:
Engineering, research and development	21,505,461	21,671,940	65,408,256	62,395,241
Selling, general & administrative	14,128,619	13,747,925	43,020,328	41,602,675
Total operating expenses	35,634,080	35,419,865	108,428,584	103,997,916
Income from operations	116,262,620	103,205,827	332,103,956	300,218,811
OTHER INCOME
Investment income	495,468	406,491	1,861,545	1,129,654
Other Income, net	(710,346)	380,289	950,304	9,958,235
Total other income	(214,878)	786,780	2,811,849	11,087,889
Income before provision for income taxes	116,047,742	103,992,607	334,915,805	311,306,700
PROVISION FOR INCOME TAXES	37,715,317	31,655,724	104,841,502	93,677,000
NET INCOME	$ 78,332,425	$ 72,336,883	$ 230,074,303	$ 217,629,700
EARNINGS PER SHARE:
Basic (in dollars per share)	$ 0.27	$ 0.25	$ 0.78	$ 0.75
Diluted (in dollars per share)	0.27	0.25	0.77	0.74
Cash Dividends Declared per Share (in dollars per share)	$ 0.085	$ 0.08	$ 0.25	$ 0.23

Unaudited Condensed Consolidat4

Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 78,332,425	$ 72,336,883	$ 230,074,303	$ 217,629,700
Other comprehensive income (loss) before tax:
Foreign currency translation adjustments	(396,686)	(269,392)	(1,038,892)	(602,131)
Unrealized losses on derivatives	(1,275,655)	0	(3,143,576)	0
Unrealized losses on available-for sales securities, net	(11,808,718)	(4,785,501)	(15,372,962)	(11,131,487)
Other comprehensive loss, before tax	(13,481,059)	(5,054,893)	(19,555,430)	(11,733,618)
Benefit for income taxes related to components of other comprehensive loss	(4,579,531)	(1,674,925)	(6,480,789)	(3,896,021)
Other comprehensive loss, net of tax	(8,901,528)	(3,379,968)	(13,074,641)	(7,837,597)
Comprehensive Income	$ 69,430,897	$ 68,956,915	$ 216,999,662	$ 209,792,103

Unaudited Condensed Consolidat5

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2015		Sep. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 230,074,303		$ 217,629,700
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	63,709,095		59,747,630
Gain on disposal of assets	(18,052)		(35,000)
Loss on disposal of assets	360,659		411,129
Gain on sale of investments	(8,390,451)		(14,964,192)
Loss on sale of investments	1,828,617		1,081,164
Deferred income taxes	(10,836,858)		225,911
Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock	16,534,607		15,569,999
Excess tax benefits from stock-based compensation	(2,411,583)		(2,615,892)
Change in operating assets and liabilities:
Accounts receivable, net	(40,194,912)		(43,365,458)
Inventories	(22,846,177)		(15,523,737)
Prepaid expenses and other	9,106,066		(13,414,445)
Accounts payable	12,435,275		12,103,087
Accrued liabilities, excluding dividends declared	33,810,991		10,603,937
Net cash provided by operating activities	283,161,580		227,453,833
Activity in available-for-sale securities:
Sales proceeds	45,787,794		68,958,662
Purchases	(34,380,942)		(63,310,363)
Plant and equipment additions	(62,282,827)		(49,994,352)
Proceeds from sale of plant and equipment	4		35,005
(Increase) in other assets	(1,931,566)		(1,213,792)
Net cash (used for) investing activities	(52,807,537)		(45,524,840)
CASH FLOWS (USED FOR) FINANCING ACTIVITIES:
Repayment of long-term debt	(30,625,000)		(5,625,000)
Issuance of common stock from stock plan transactions	20,008,358		19,184,437
Cash dividends paid	(72,150,137)		(64,209,453)
Repurchases of common stock	(82,900,454)		(9,999,957)
Excess tax benefits from stock-based compensation	2,411,583		2,615,892
Net cash (used for) financing activities	(163,255,650)		(58,034,081)
NET INCREASE IN CASH AND CASH EQUIVALENTS	67,098,393		123,894,912
CASH AND CASH EQUIVALENTS, beginning of period	497,429,804	[1]	309,591,724
CASH AND CASH EQUIVALENTS, end of period	$ 564,528,197		$ 433,486,636
[1]	Note: The condensed consolidated balance sheet at December 31, 2014 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.

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements included herein have been prepared by the Company, pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted pursuant to such rules and regulations, although the Company believes that the disclosures are adequate to make the information presented not misleading. It is suggested that these unaudited condensed consolidated financial statements be read in conjunction with the financial statements and notes thereto included in the Company's 2014 annual report on Form 10-K. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all adjustments, consisting of only a normal and recurring nature, necessary to present fairly the financial position of the Company as of September 30, 2015 , and the results of operations and cash flows for the interim periods presented.

Adoption of New Accounting Stan

Adoption of New Accounting Standards	9 Months Ended
	Sep. 30, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Adoption of New Accounting Standards	Adoption of New Accounting Standards In May 2014 the Financial Accounting Standards Board (FASB) issued the Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606) , that will supersede nearly all existing revenue recognition guidance under US GAAP. The core principle of the guidance is that an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The standard was to originally be effective for public entities for annual and interim periods beginning after December 15, 2016. On July 9, 2015 the FASB decided to defer by one year the effective dates of the new standard for both public and nonpublic entities reporting under US GAAP. Early adoption would be permitted for all entities, but not before the original public entity effective date (i.e. annual and interim periods beginning after December 15, 2016). Entities can choose to apply the standard using either the full retrospective approach or a modified retrospective approach. Entities electing the full retrospective adoption will apply the standard to each period presented in the financial statements. This means that entities will have to apply the new guidance as if it had been in effect since the inception of all its contracts with customers presented in the financial statements. Entities that elect the modified retrospective approach will apply the guidance retrospectively only to the most current period presented in the financial statements. This means that entities will have to recognize the cumulative effect of initially applying the new standard as an adjustment to the opening balance of retained earnings at the date of initial application. The new revenue standard will be applied to contracts that are in progress at the date of initial application. The Company is currently evaluating which adoption method it plans to use and is assessing the potential effect the new standard will have on its consolidated financial statements.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill represents the cost of an acquisition in excess of the fair values assigned to identifiable net assets acquired. The Company recorded Goodwill of $307.4 million as part of the HomeLink ® acquisition. The carrying value of Goodwill as of December 31, 2014 and September 30, 2015 was $307.4 million . In addition to annual impairment testing, which was performed in the fourth quarter of 2014 and indicated that the estimated fair value of the Automotive reporting unit exceeded its corresponding carrying amount including goodwill, the Company continuously monitors for events and circumstances that could negatively impact the key assumptions in determining fair value thus resulting in the need for interim impairment testing, including long-term revenue growth projections, profitability, discount rates, recent market valuations from transactions by comparable companies, volatility in the Company's market capitalization, and general industry, market and macroeconomic conditions. No such events or circumstances in the most recently completed quarter indicated the need for interim impairment testing. The patents and intangible assets and related change in carrying values are set forth in the table below: As of September 30, 2015 : Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 30,720,542 $ (13,092,594 ) $ 17,627,948 various Other Intangible Assets HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (30,000,000 ) 150,000,000 12 years Existing Customer Platforms 43,000,000 (8,600,000 ) 34,400,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total Other Intangible Assets $ 371,000,000 $ (38,600,000 ) $ 332,400,000 Total Patents & Other Intangible Assets $ 401,720,542 $ (51,692,594 ) $ 350,027,948 As of December 31, 2014: Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 30,132,116 $ (11,065,153 ) $ 19,066,963 various HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (18,750,000 ) $ 161,250,000 12 years Existing Customer Platforms 43,000,000 (5,375,000 ) $ 37,625,000 10 years Exclusive Licensing Agreement 96,000,000 — $ 96,000,000 Indefinite Total other identifiable intangible assets $ 371,000,000 $ (24,125,000 ) $ 346,875,000 Total Patents & Other Intangible Assets $ 401,132,116 $ (35,190,153 ) $ 365,941,963 Amortization expense on patents and intangible assets was approximately $5.5 million and $16.5 million during the three and nine month periods ended September 30, 2015 , respectively, compared to approximately $5.5 million and $16.5 million for the same periods ended September 30, 2014 , respectively. Excluding the impact of any future acquisitions, the Company continues to estimate amortization expense for each of the years ended December 31, 2015, 2016, 2017, 2018 and 2019 to be approximately $22 million annually.

Investments

Investments	9 Months Ended
	Sep. 30, 2015
Investments [Abstract]
Investments	Investments The Company follows the provisions of ASC 820, “Fair Value Measurements and Disclosures” for its financial assets and liabilities, and for its non-financial assets and liabilities subject to fair value measurements. ASC 820 provides a framework for measuring the fair value of assets and liabilities. This framework is intended to provide increased consistency in how fair value determinations are made under various existing accounting standards that permit, or in some cases, require estimates of fair-market value. This standard also expanded financial statement disclosure requirements about a company’s use of fair-value measurements, including the effect of such measure on earnings. The cost of securities sold is based on the specific identification method. The Company’s investment securities (common stocks and mutual funds) are classified as available for sale and are stated at fair value based on quoted market prices, and as such are classified as Level 1 assets. Assets or liabilities that have recurring fair value measurements are shown below as of September 30, 2015 , and December 31, 2014 : As of September 30, 2015 : Fair Value Measurements at Reporting Date Using Total as of Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Description September 30, 2015 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 564,528,197 $ 564,528,197 $ — $ — Short-Term Investments: Other 335 335 — — Long-Term Investments: Common Stocks 24,128,497 24,128,497 — — Mutual Funds – Equity 70,296,089 70,296,089 — — Total $ 658,953,118 $ 658,953,118 $ — $ — As of December 31, 2014 : Fair Value Measurements at Reporting Date Using Total as of Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Description December 31, 2014 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 497,429,804 $ 497,429,804 $ — $ — Short-Term Investments: Other 1,021 1,021 — — Long-Term Investments: Common Stocks 24,648,451 24,648,451 — — Mutual Funds – Equity 89,994,116 89,994,116 — — Total $ 612,073,392 $ 612,073,392 $ — $ — The amortized cost, unrealized gains and losses, and market value of investment securities are shown as of September 30, 2015 , and December 31, 2014 : As of September 30, 2015 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Other $ 335 $ — $ — $ 335 Long-Term Investments: Common Stocks 21,181,972 4,667,521 (1,720,996 ) 24,128,497 Mutual Funds – Equity 71,895,080 1,917,534 (3,516,525 ) 70,296,089 Total $ 93,077,387 $ 6,585,055 $ (5,237,521 ) $ 94,424,921 As of December 31, 2014 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Other $ 1,021 $ — $ — $ 1,021 Long-Term Investments: Common Stocks 17,069,742 7,933,717 (355,008 ) 24,648,451 Mutual Funds – Equity 80,852,329 9,922,204 (780,417 ) 89,994,116 Total $ 97,923,092 $ 17,855,921 $ (1,135,425 ) $ 114,643,588 Unrealized losses on investments as of September 30, 2015 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 5,237,521 $ 58,061,443 Unrealized losses on investments as of December 31, 2014 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 1,135,425 $ 19,972,258 ASC 320, “Accounting for Certain Investments in Debt and Equity Securities”, as amended, provides guidance on determining when an investment is other than temporarily impaired. The Company reviews its equity investment portfolio for any unrealized losses that would be deemed other-than-temporary and require the recognition of an impairment loss in income. If the cost of an investment exceeds its fair value, the Company evaluates, among other factors, general market conditions, the duration and extent to which the fair value is less than cost, and the Company’s intent and ability to hold the investments. Management also considers the type of security, related-industry and sector performance, as well as published investment ratings and analyst reports, to evaluate its portfolio. Once a decline in fair value is determined to be other than temporary, an impairment charge is recorded and a new cost basis in the investment is established. If market, industry, and/or investee conditions deteriorate, the Company may incur future impairments. No equity investment losses were considered to be other than temporary during the periods presented.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2015
Inventory Disclosure [Abstract]
Inventories	Inventories consisted of the following at the respective balance sheet dates: September 30, 2015 December 31, 2014 Raw materials $ 105,026,208 $ 90,780,320 Work-in-process 26,119,390 24,135,944 Finished goods 33,458,465 26,841,620 Total Inventory $ 164,604,063 $ 141,757,884

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The following table reconciles the numerators and denominators used in the calculation of basic and diluted earnings per share (EPS), adjusted for the 2 for 1 stock split effected in the form of a 100% stock dividend issued on December 31, 2014: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Numerators: Numerator for both basic and diluted EPS, net income $ 78,332,425 $ 72,336,883 $ 230,074,303 $ 217,629,700 Denominators: Denominator for basic EPS, weighted-average shares outstanding 292,589,866 290,969,434 293,742,028 290,383,296 Potentially dilutive shares resulting from stock plans 2,787,612 1,906,518 3,252,544 2,353,616 Denominator for diluted EPS 295,377,478 292,875,952 296,994,572 292,736,912 Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive 3,756,369 7,698,848 1,611,900 2,949,114

Stock-Based Compensation Plans

Stock-Based Compensation Plans	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans As of September 30, 2015 , the Company had four equity incentive plans which include two stock option plans, a restricted stock plan and an employee stock purchase plan. All plans and any prior material amendments thereto have previously been approved by shareholders. Readers should refer to Note 5 of our consolidated financial statements in our Annual Report on Form 10-K for the calendar year ended December 31, 2014 , for additional information related to these stock-based compensation plans. The Company recognized compensation expense for share-based payments of $4,404,297 and $13,979,297 for the three and nine months ended September 30, 2015 , respectively and $4,778,693 and $13,391,738 for the three and nine months ended September 30, 2014 , respectively. Compensation cost capitalized as part of inventory as of September 30, 2015 , was $279,903 . Employee Stock Option Plan The Company has an employee stock option plan covering 24,000,000 shares of common stock. The purpose of the plan is to provide an opportunity to use stock options as a means of recruiting new managerial and technical personnel and as a means for retaining certain employees of the Company and allow them to purchase shares of common stock of the Corporation and thereby have an additional incentive to contribute to the prosperity of the Company. The fair value of each option grant in the employee stock option plan was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions for the indicated periods: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Dividend Yield (1) 2.12 % 2.36 % 2.13 % 2.32 % Expected volatility (2) 35.81 % 37.70 % 36.10 % 38.73 % Risk-free interest rate (3) 1.37 % 1.79 % 1.56 % 1.81 % Expected term of options (years) (4) 4.31 4.38 4.97 4.84 Weighted-avg. grant date fair value $3.94 $3.60 $4.47 $4.13 (1) Represents the Company’s estimated cash dividend yield over the expected term of option grant . (2) Amount is determined based on analysis of historical price volatility of the Company’s common stock. The expected volatility is based on the daily percentage change in the price of the stock over a period equal to the expected term of the option grant. (3) Represents the U.S. Treasury yield over the expected term of the option grant. (4) Represents the period of time that options granted are expected to be outstanding. Based on analysis of historical option exercise activity, the Company has determined that all employee groups exhibit similar exercise and post-vesting termination behavior. Under the employee stock option plan, the option exercise price equals the stock’s market price on date of grant. The options vest after one to five years, and expire after five to seven years. As of September 30, 2015 , there was $22,971,517 of unrecognized compensation cost related to share-based payments which is expected to be recognized over the vesting periods. Non-employee Director Stock Option Plan The Company has a non-employee director stock option plan covering 1,000,000 shares of common stock. As of September 30, 2015 , there was $71,922 of unrecognized compensation cost under the non-employee director plan related to share-based payments. The Company has granted options on 315,000 shares under the non-employee director plan through September 30, 2015 . Under the non-employee director plan, the option exercise price equals the stock’s market price on the date of grant. The options vest after six months , and expire after ten years . Employee Stock Purchase Plan The Company has an employee stock purchase plan covering 2,000,000 shares of common stock. Under the plan, the Company sells shares at 85% of the stock’s market price at date of purchase. Under ASC 718, the 15% discounted value is recognized as compensation expense. Restricted Stock Plan The Company has a restricted stock plan covering 9,000,000 shares of common stock. The purpose of the restricted stock plan is to permit grants of shares, subject to restrictions, to key employees of the Company as a means of retaining and rewarding them for long-term performance and to increase their ownership in the Company. Shares awarded under the restricted stock plan entitle the shareholder to all rights of common stock ownership except that the shares may not be sold, transferred, pledged, exchanged or otherwise disposed of during the restriction period. The restriction period is determined by the Compensation Committee, appointed by the Board of Directors, but may not exceed ten years under the terms of the plan. As of September 30, 2015 , the Company had unearned stock-based compensation of $11,698,198 associated with these restricted stock grants. The unearned stock-based compensation related to these grants is being amortized to compensation expense over the applicable restriction periods. Amortization expense from restricted stock grants in the three months and nine months ended September 30, 2015 was $905,772 and $2,555,310 .

Comprehensive Income

Comprehensive Income	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Comprehensive Income	Comprehensive Income Comprehensive income reflects the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. For the Company, comprehensive income represents net income adjusted for unrealized gains and losses on certain investments and foreign currency translation adjustments. The following table presents the net changes in the Company's accumulated other comprehensive income (loss) by component: (All amounts shown are net of tax). Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Foreign currency translation adjustments: Balance at beginning of period $ 761,692 $ 2,175,183 $ 1,403,899 $ 2,507,922 Other Comprehensive (loss) income before reclassifications (396,685 ) (269,392 ) (1,038,892 ) (602,131 ) Amounts reclassified from accumulated other comprehensive income — — — — Net current-period change (396,685 ) (269,392 ) (1,038,892 ) (602,131 ) Balance at end of period 365,007 1,905,791 365,007 1,905,791 Unrealized gains (losses) on available-for-sale securities: Balance at beginning of period 8,551,564 15,342,551 10,868,322 19,467,441 Other Comprehensive income (loss) before reclassifications (6,353,685 ) (1,604,338 ) (5,727,233 ) 1,788,502 Amounts reclassified from accumulated other comprehensive income (1,321,982 ) (1,506,238 ) (4,265,192 ) (9,023,968 ) Net current-period change (7,675,667 ) (3,110,576 ) (9,992,425 ) (7,235,466 ) Balance at end of period 875,897 12,231,975 875,897 12,231,975 Unrealized gains (losses) on derivatives: Balance at beginning of period (2,173,354 ) — (959,206 ) — Other comprehensive income (loss) before reclassifications (1,113,648 ) — (2,327,796 ) — Amounts reclassified from accumulated other comprehensive income 284,472 — 284,472 — Net current-period change (829,176 ) — (2,043,324 ) — Balance at end of period (3,002,530 ) — (3,002,530 ) — Accumulated other comprehensive income (loss), end of period $ (1,761,626 ) $ 14,137,766 $ (1,761,626 ) $ 14,137,766 The following table presents details of reclassifications out of other comprehensive income for the three and nine months ended September 30, 2015 and 2014 . Details about Accumulated Other Comprehensive Income Components Amounts Reclassified from Other Comprehensive Income Affected Line item in the Statement of Consolidated Income Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Unrealized gains on available-for-sale securities Realized gain on sale of securities $ 2,033,819 $ 2,317,289 $ 6,561,834 $ 13,883,028 Other, net Provision for Income Taxes (711,837 ) (811,051 ) (2,296,642 ) (4,859,060 ) Provision for Income Taxes $ 1,321,982 $ 1,506,238 $ 4,265,192 $ 9,023,968 Net of tax Unrealized gains (losses) on derivatives Realized loss on interest rate swap $ (437,650 ) $ — $ (437,650 ) $ — Other, net Provision for Income Taxes 153,178 — 153,178 — Provision for Income Taxes $ (284,472 ) $ — $ (284,472 ) $ — Net of tax Total reclassifications for the period $ 1,037,510 $ 1,506,238 $ 3,980,720 $ 9,023,968 Net of tax

Debt and Financing Arrangements

Debt and Financing Arrangements	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Debt and Financing Arrangements	Debt and Financing Arrangements Credit Agreement On September 27, 2013, the Company entered into a Credit Agreement (the “Credit Agreement”) with certain banks and agents. Pursuant to the Credit Agreement, the Company is borrower under a $150 million senior revolving credit facility (“Revolver”) and a $150 million term loan facility (“Term Loan”). Under the terms of the Credit Agreement, the Company is entitled, to further request an additional aggregate principal amount of up to $75 million , subject to the satisfaction of certain conditions. In addition, the Company is entitled to the benefit of swing loans from amounts otherwise available under the Revolver in the aggregate principal amount of up to $20 million and to request Letters of Credit from amounts otherwise available under the Revolver in the aggregate principle amount up to $20 million , both subject to certain conditions. The obligations of the Company under the Credit Agreement are not secured, but are subject to certain covenants. The Revolver expires and the Term Loan matures on September 27, 2018. During the three and nine months ended September 30, 2015 , the Company made principal repayments of $26.9 million and $30.6 million respectively, plus accrued interest, on the Term Loan. The aforementioned payments include additional payments made by the company of $25.0 million during the three months ended September 30, 2015 on the Revolver, which were in addition to scheduled amounts due. The Company used cash and cash equivalents to fund the payments. As of September 30, 2015 , $100.8 million was outstanding on the Revolver with availability of an additional $49.2 million . Under current terms of the Term Loan, the Company will make principal repayments of $7.5 million annually through the maturity date of the Term Loan. As of September 30, 2015 , $135.0 million was outstanding under the Term Loan. As of September 30, 2015 , the borrowing rate on both its Term Loan and Revolver are derived from the one month LIBOR, and based on the Company's leverage ratio as of September 30, 2015 , the interest rate on its borrowings is equal to 1.19% . Interest expense are netted within the "Other, net" section of the Condensed Consolidated Statements of Income and were $1.3 million and $3.0 million during the three and nine months ended September 30, 2015 , respectively, and $0.9 million and $2.7 million during the three and nine months ended September 30, 2014 , respectively. The Credit Agreement contains customary representations and warranties and certain covenants that place certain limitations on the Company. As of September 30, 2015 , the Company was in compliance with its covenants under the Credit Agreement. Interest Rate Swap On October 1, 2014 the Company entered into an interest rate swap transaction with a bank (the “Counterparty”). The Counterparty is among the syndicate of lenders under the existing Credit Agreement entered into on September 27, 2013. The Company entered into the interest rate swap transaction to mitigate the Company’s floating rate interest risk on an aggregate of $150 million of the Company’s debt that is currently outstanding under the Credit Agreement. The interest rate swap has an effective date of July 31, 2015 and a termination date of September 27, 2018 (which is the expiration date of the Credit Agreement). The Company is required to make certain monthly fixed rate payments to the Counterparty calculated on a notional amount of $150 million for the rate swap, while the Counterparty is obligated to make monthly floating rate payments to the Company referencing the same notional amount. The interest rate swap transaction has the effect of fixing the annual interest rate payable on $150 million of the Company’s outstanding debt under its existing credit facility to 1.89% , as of the effective date. The notional amounts of the interest rate swap agreement are used to measure interest to be paid or received and do not represent the amount of exposure to credit loss. This derivative instrument has been designated as a cash flow hedge of the variable interest payments on the related debt. Notwithstanding the terms of the interest rate swap transaction, the Company is ultimately obligated for all amounts due and payable under its existing Credit Agreement. The notional amount of the Company's derivative instruments are as follows: September 30, 2015 December 31, 2014 Interest Rate swap $ 150,000,000 $ 150,000,000 The following table sets forth financial assets and liabilities measured at fair value related to the interest rate swap agreement and the respective pricing levels to which the fair value measurements are classified within the fair value hierarchy. The Company uses the market approach to derive the value of its level 2 fair value measurements. Interest rate swaps are valued using publicized swap curves. Fair Value Measurements Quoted Prices with Other Observable Inputs (Level 2) September 30, 2015 December 31, 2014 Financial assets: Interest Rate Swap Asset $ — $ — Financial Liabilities: Interest Rate Swap Liability (Other Accrued Liabilities) $ 4,619,278 $ 1,475,702 Based on loan balances as of September 30, 2015 and the effective date of July 31, 2015 of the interest rate swap, a one percent increase in the Company's borrowing rate would increase net interest expense paid by the Company on its borrowings by approximately $0.8 million dollars on an annual basis.

Equity

Equity	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Equity	Equity The decrease in common stock during the nine months ended September 30, 2015 , was primarily due to share repurchases of 4,885,077 shares pursuant to the Company's previously announced share repurchase plan, which was partially offset by the issuance of 1,875,967 shares of the Company’s common stock under the Company’s stock-based compensation plans for a net decrease of 3,009,110 shares. The Company announced a $.005 per share increase in its quarterly cash dividend rate during the second quarter of 2015. As such, the Company recorded a cash dividend of $0.085 during the second and third quarters of 2015 as compared per to $.08 per share during the first quarter of 2015. The third quarter dividend of $24.8 million , was declared on August 31, 2015 , and was paid on October 16, 2015 . Stock Split On December 5, 2014, the Company announced that its Board of Directors approved a two -for-one split of our outstanding shares of common stock to be effected in the form of a 100% stock dividend. On December 31, 2014, shareholders of record at the close of business on December 17, 2014, were issued one additional share of common stock for each share owned by such shareholder. The stock split increased the number of shares of common stock outstanding from approximately 147.6 million to approximately 295.2 million . Share and per-share amounts (including stock options and restricted stock) shown in the consolidated financial statements and related notes reflect the split. The total number of authorized common shares and the par value thereof was not changed by the split.

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies The Company is periodically involved in legal proceedings, legal actions and claims arising in the normal course of business, including proceedings relating to product liability, intellectual property, safety and health, employment and other matters. Such matters are subject to many uncertainties and outcomes are not predictable. The Company does not believe, however, that at the current time any of these matters constitute material pending legal proceedings that will have a material adverse effect on the financial position or future results of operations of the Company.

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company's automotive segment develops and manufactures electro-optic products, including: automatic-dimming rearview mirrors with and without electronic features for the automotive industry; non-auto dimming rearview automotive mirrors with and without electronic features; and other electronics. The Company also develops and manufactures variably dimming windows for the aerospace industry and fire protection products for the commercial construction industry, which are combined into the "Other" segment shown below. Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Revenue: Automotive Products $ 379,889,957 $ 341,786,404 $ 1,111,009,546 $ 997,708,190 Other 9,939,182 9,127,508 27,015,525 27,382,030 Total $ 389,829,139 $ 350,913,912 $ 1,138,025,071 $ 1,025,090,220 Income from operations: Automotive Products $ 112,238,938 $ 100,053,622 $ 322,289,461 $ 290,348,056 Other 4,023,682 3,152,205 9,814,495 9,870,755 Total $ 116,262,620 $ 103,205,827 $ 332,103,956 $ 300,218,811

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate was 32.5% in the third quarter of 2015 compared to 30.4% for the same period in 2014. Effective tax rates differ from statutory federal income tax rates, primarily due to the domestic manufacturing deduction, provisions for state and local income taxes and permanent tax differences. The increase in the effective tax rate from the third quarter of 2015 compared to the third quarter of 2014 is primarily due to incremental research and development tax credits related to the 2013 calendar year of $1.8 million recognized during the third quarter of 2014 as a result of an amended tax filing at that time.

Stock Split

Stock Split	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Stock Split	Equity The decrease in common stock during the nine months ended September 30, 2015 , was primarily due to share repurchases of 4,885,077 shares pursuant to the Company's previously announced share repurchase plan, which was partially offset by the issuance of 1,875,967 shares of the Company’s common stock under the Company’s stock-based compensation plans for a net decrease of 3,009,110 shares. The Company announced a $.005 per share increase in its quarterly cash dividend rate during the second quarter of 2015. As such, the Company recorded a cash dividend of $0.085 during the second and third quarters of 2015 as compared per to $.08 per share during the first quarter of 2015. The third quarter dividend of $24.8 million , was declared on August 31, 2015 , and was paid on October 16, 2015 . Stock Split On December 5, 2014, the Company announced that its Board of Directors approved a two -for-one split of our outstanding shares of common stock to be effected in the form of a 100% stock dividend. On December 31, 2014, shareholders of record at the close of business on December 17, 2014, were issued one additional share of common stock for each share owned by such shareholder. The stock split increased the number of shares of common stock outstanding from approximately 147.6 million to approximately 295.2 million . Share and per-share amounts (including stock options and restricted stock) shown in the consolidated financial statements and related notes reflect the split. The total number of authorized common shares and the par value thereof was not changed by the split.

Goodwill and Other Intangible20

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	The patents and intangible assets and related change in carrying values are set forth in the table below: As of September 30, 2015 : Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 30,720,542 $ (13,092,594 ) $ 17,627,948 various Other Intangible Assets HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (30,000,000 ) 150,000,000 12 years Existing Customer Platforms 43,000,000 (8,600,000 ) 34,400,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total Other Intangible Assets $ 371,000,000 $ (38,600,000 ) $ 332,400,000 Total Patents & Other Intangible Assets $ 401,720,542 $ (51,692,594 ) $ 350,027,948 As of December 31, 2014: Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 30,132,116 $ (11,065,153 ) $ 19,066,963 various HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (18,750,000 ) $ 161,250,000 12 years Existing Customer Platforms 43,000,000 (5,375,000 ) $ 37,625,000 10 years Exclusive Licensing Agreement 96,000,000 — $ 96,000,000 Indefinite Total other identifiable intangible assets $ 371,000,000 $ (24,125,000 ) $ 346,875,000 Total Patents & Other Intangible Assets $ 401,132,116 $ (35,190,153 ) $ 365,941,963

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2015
Investments [Abstract]
Investment Securities Stated at Fair Value	Assets or liabilities that have recurring fair value measurements are shown below as of September 30, 2015 , and December 31, 2014 : As of September 30, 2015 : Fair Value Measurements at Reporting Date Using Total as of Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Description September 30, 2015 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 564,528,197 $ 564,528,197 $ — $ — Short-Term Investments: Other 335 335 — — Long-Term Investments: Common Stocks 24,128,497 24,128,497 — — Mutual Funds – Equity 70,296,089 70,296,089 — — Total $ 658,953,118 $ 658,953,118 $ — $ — As of December 31, 2014 : Fair Value Measurements at Reporting Date Using Total as of Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Description December 31, 2014 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 497,429,804 $ 497,429,804 $ — $ — Short-Term Investments: Other 1,021 1,021 — — Long-Term Investments: Common Stocks 24,648,451 24,648,451 — — Mutual Funds – Equity 89,994,116 89,994,116 — — Total $ 612,073,392 $ 612,073,392 $ — $ —
Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value of Investment Securities	The amortized cost, unrealized gains and losses, and market value of investment securities are shown as of September 30, 2015 , and December 31, 2014 : As of September 30, 2015 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Other $ 335 $ — $ — $ 335 Long-Term Investments: Common Stocks 21,181,972 4,667,521 (1,720,996 ) 24,128,497 Mutual Funds – Equity 71,895,080 1,917,534 (3,516,525 ) 70,296,089 Total $ 93,077,387 $ 6,585,055 $ (5,237,521 ) $ 94,424,921 As of December 31, 2014 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Other $ 1,021 $ — $ — $ 1,021 Long-Term Investments: Common Stocks 17,069,742 7,933,717 (355,008 ) 24,648,451 Mutual Funds – Equity 80,852,329 9,922,204 (780,417 ) 89,994,116 Total $ 97,923,092 $ 17,855,921 $ (1,135,425 ) $ 114,643,588
Schedule of Unrealized Loss on Investments	Unrealized losses on investments as of September 30, 2015 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 5,237,521 $ 58,061,443 Unrealized losses on investments as of December 31, 2014 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 1,135,425 $ 19,972,258

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2015
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories consisted of the following at the respective balance sheet dates: September 30, 2015 December 31, 2014 Raw materials $ 105,026,208 $ 90,780,320 Work-in-process 26,119,390 24,135,944 Finished goods 33,458,465 26,841,620 Total Inventory $ 164,604,063 $ 141,757,884

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Schedule of Earnings Per Share Basic And Diluted	The following table reconciles the numerators and denominators used in the calculation of basic and diluted earnings per share (EPS), adjusted for the 2 for 1 stock split effected in the form of a 100% stock dividend issued on December 31, 2014: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Numerators: Numerator for both basic and diluted EPS, net income $ 78,332,425 $ 72,336,883 $ 230,074,303 $ 217,629,700 Denominators: Denominator for basic EPS, weighted-average shares outstanding 292,589,866 290,969,434 293,742,028 290,383,296 Potentially dilutive shares resulting from stock plans 2,787,612 1,906,518 3,252,544 2,353,616 Denominator for diluted EPS 295,377,478 292,875,952 296,994,572 292,736,912 Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive 3,756,369 7,698,848 1,611,900 2,949,114

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted-Average Assumptions For The Employee Stock Option Plan	The fair value of each option grant in the employee stock option plan was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions for the indicated periods: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Dividend Yield (1) 2.12 % 2.36 % 2.13 % 2.32 % Expected volatility (2) 35.81 % 37.70 % 36.10 % 38.73 % Risk-free interest rate (3) 1.37 % 1.79 % 1.56 % 1.81 % Expected term of options (years) (4) 4.31 4.38 4.97 4.84 Weighted-avg. grant date fair value $3.94 $3.60 $4.47 $4.13 (1) Represents the Company’s estimated cash dividend yield over the expected term of option grant . (2) Amount is determined based on analysis of historical price volatility of the Company’s common stock. The expected volatility is based on the daily percentage change in the price of the stock over a period equal to the expected term of the option grant. (3) Represents the U.S. Treasury yield over the expected term of the option grant. (4) Represents the period of time that options granted are expected to be outstanding. Based on analysis of historical option exercise activity, the Company has determined that all employee groups exhibit similar exercise and post-vesting termination behavior.

Comprehensive Income (Tables)

Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Schedule of net changes in the Company's accumulated other comprehensive income by component	The following table presents the net changes in the Company's accumulated other comprehensive income (loss) by component: (All amounts shown are net of tax). Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Foreign currency translation adjustments: Balance at beginning of period $ 761,692 $ 2,175,183 $ 1,403,899 $ 2,507,922 Other Comprehensive (loss) income before reclassifications (396,685 ) (269,392 ) (1,038,892 ) (602,131 ) Amounts reclassified from accumulated other comprehensive income — — — — Net current-period change (396,685 ) (269,392 ) (1,038,892 ) (602,131 ) Balance at end of period 365,007 1,905,791 365,007 1,905,791 Unrealized gains (losses) on available-for-sale securities: Balance at beginning of period 8,551,564 15,342,551 10,868,322 19,467,441 Other Comprehensive income (loss) before reclassifications (6,353,685 ) (1,604,338 ) (5,727,233 ) 1,788,502 Amounts reclassified from accumulated other comprehensive income (1,321,982 ) (1,506,238 ) (4,265,192 ) (9,023,968 ) Net current-period change (7,675,667 ) (3,110,576 ) (9,992,425 ) (7,235,466 ) Balance at end of period 875,897 12,231,975 875,897 12,231,975 Unrealized gains (losses) on derivatives: Balance at beginning of period (2,173,354 ) — (959,206 ) — Other comprehensive income (loss) before reclassifications (1,113,648 ) — (2,327,796 ) — Amounts reclassified from accumulated other comprehensive income 284,472 — 284,472 — Net current-period change (829,176 ) — (2,043,324 ) — Balance at end of period (3,002,530 ) — (3,002,530 ) — Accumulated other comprehensive income (loss), end of period $ (1,761,626 ) $ 14,137,766 $ (1,761,626 ) $ 14,137,766
Schedule of reclassifications out of other comprehensive income	The following table presents details of reclassifications out of other comprehensive income for the three and nine months ended September 30, 2015 and 2014 . Details about Accumulated Other Comprehensive Income Components Amounts Reclassified from Other Comprehensive Income Affected Line item in the Statement of Consolidated Income Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Unrealized gains on available-for-sale securities Realized gain on sale of securities $ 2,033,819 $ 2,317,289 $ 6,561,834 $ 13,883,028 Other, net Provision for Income Taxes (711,837 ) (811,051 ) (2,296,642 ) (4,859,060 ) Provision for Income Taxes $ 1,321,982 $ 1,506,238 $ 4,265,192 $ 9,023,968 Net of tax Unrealized gains (losses) on derivatives Realized loss on interest rate swap $ (437,650 ) $ — $ (437,650 ) $ — Other, net Provision for Income Taxes 153,178 — 153,178 — Provision for Income Taxes $ (284,472 ) $ — $ (284,472 ) $ — Net of tax Total reclassifications for the period $ 1,037,510 $ 1,506,238 $ 3,980,720 $ 9,023,968 Net of tax

Debt and Financing Arrangemen26

Debt and Financing Arrangements (Tables)	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Schedule of notional amount of the Company's derivative instruments	The notional amount of the Company's derivative instruments are as follows: September 30, 2015 December 31, 2014 Interest Rate swap $ 150,000,000 $ 150,000,000
Schedule of financial assets and liabilities measured at fair value in the consolidated balance sheets	The Company uses the market approach to derive the value of its level 2 fair value measurements. Interest rate swaps are valued using publicized swap curves. Fair Value Measurements Quoted Prices with Other Observable Inputs (Level 2) September 30, 2015 December 31, 2014 Financial assets: Interest Rate Swap Asset $ — $ — Financial Liabilities: Interest Rate Swap Liability (Other Accrued Liabilities) $ 4,619,278 $ 1,475,702

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Schedule of Automotive and Other Segment Reporting	The Company also develops and manufactures variably dimming windows for the aerospace industry and fire protection products for the commercial construction industry, which are combined into the "Other" segment shown below. Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Revenue: Automotive Products $ 379,889,957 $ 341,786,404 $ 1,111,009,546 $ 997,708,190 Other 9,939,182 9,127,508 27,015,525 27,382,030 Total $ 389,829,139 $ 350,913,912 $ 1,138,025,071 $ 1,025,090,220 Income from operations: Automotive Products $ 112,238,938 $ 100,053,622 $ 322,289,461 $ 290,348,056 Other 4,023,682 3,152,205 9,814,495 9,870,755 Total $ 116,262,620 $ 103,205,827 $ 332,103,956 $ 300,218,811

Goodwill and Other Intangible28

Goodwill and Other Intangible Assets (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014		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, 2015	22,000,000		22,000,000
HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Goodwill							$ 307,400,000
Accumulated amortization	38,600,000		38,600,000		24,125,000
Amortization expense, 2016	22,000,000		22,000,000
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
Gentex Patents
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Accumulated amortization	13,092,594		13,092,594		11,065,153
Patents and Other Intangible Assets
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Accumulated amortization	51,692,594		51,692,594		$ 35,190,153
Patents and Other Intangible Assets | HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Amortization expense	$ 5,500,000	$ 5,500,000	$ 16,500,000	$ 16,500,000
[1]	Note: The condensed consolidated balance sheet at December 31, 2014 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.

Goodwill and Other Intangible29

Goodwill and Other Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 332,400,000	$ 346,875,000	[1]
Gentex Patents
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	30,720,542	30,132,116
Finite-lived intangible assets, accumulated amortization	(13,092,594)	(11,065,153)
Finite-lived intangible assets, net	17,627,948	19,066,963
Patents and Other Intangible Assets
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	(51,692,594)	(35,190,153)
Intangible assets, gross	401,720,542	401,132,116
Intangible assets, net	350,027,948	365,941,963
HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	(38,600,000)	(24,125,000)
Intangible assets, gross	371,000,000	371,000,000
Intangible assets, net	332,400,000	346,875,000
HomeLink® | Homelink Technology
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	180,000,000	180,000,000
Finite-lived intangible assets, accumulated amortization	(30,000,000)	(18,750,000)
Finite-lived intangible assets, net	$ 150,000,000	$ 161,250,000
HomeLink® | Homelink Technology | Minimum [Member]
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	12 years	12 years
HomeLink® | Existing Customer Platforms
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 43,000,000	$ 43,000,000
Finite-lived intangible assets, accumulated amortization	(8,600,000)	(5,375,000)
Finite-lived intangible assets, net	$ 34,400,000	$ 37,625,000
Finite-lived intangible asset, useful life	10 years	10 years
HomeLink® | HomeLink Trade Names and Trademarks
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 52,000,000	$ 52,000,000
HomeLink® | Exclusive Licensing Agreement
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 96,000,000	$ 96,000,000
[1]	Note: The condensed consolidated balance sheet at December 31, 2014 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.

Investments (Schedule of Amorti

Investments (Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value of Investment Securities) (Details) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	$ 564,528,197	$ 497,429,804
Cost	93,077,387	97,923,092
Unrealized Gains	6,585,055	17,855,921
Unrealized Losses	(5,237,521)	(1,135,425)
Market Value	94,424,921	114,643,588
Investments and Cash	658,953,118	612,073,392
Short-term Investments [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	335	1,021
Unrealized Gains	0	0
Unrealized Losses	0	0
Market Value	335	1,021
Long-Term Investments [Member] | Common Stock
Schedule of Available-for-sale Securities [Line Items]
Cost	21,181,972	17,069,742
Unrealized Gains	4,667,521	7,933,717
Unrealized Losses	(1,720,996)	(355,008)
Market Value	24,128,497	24,648,451
Long-Term Investments [Member] | Mutual Funds – Equity
Schedule of Available-for-sale Securities [Line Items]
Cost	71,895,080	80,852,329
Unrealized Gains	1,917,534	9,922,204
Unrealized Losses	(3,516,525)	(780,417)
Market Value	70,296,089	89,994,116
Fair Value, Inputs, Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	564,528,197	497,429,804
Investments and Cash	658,953,118	612,073,392
Fair Value, Inputs, Level 1 [Member] | Short-term Investments [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	335	1,021
Fair Value, Inputs, Level 1 [Member] | Long-Term Investments [Member] | Common Stock
Schedule of Available-for-sale Securities [Line Items]
Market Value	24,128,497	24,648,451
Fair Value, Inputs, Level 1 [Member] | Long-Term Investments [Member] | Mutual Funds – Equity
Schedule of Available-for-sale Securities [Line Items]
Market Value	70,296,089	89,994,116
Fair Value, Inputs, Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	0	0
Investments and Cash	0	0
Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 2 [Member] | Long-Term Investments [Member] | Common Stock
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 2 [Member] | Long-Term Investments [Member] | Mutual Funds – Equity
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	0	0
Investments and Cash	0	0
Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] | Long-Term Investments [Member] | Common Stock
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] | Long-Term Investments [Member] | Mutual Funds – Equity
Schedule of Available-for-sale Securities [Line Items]
Market Value	$ 0	$ 0

Investments (Schedule of Unreal

Investments (Schedule of Unrealized Loss on Investments) (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Investments [Abstract]
Aggregate Unrealized Losses, Less than one year	$ 5,237,521	$ 1,135,425
Aggregate Fair Value, Less than one year	58,061,443	19,972,258
Equity investment losses were considered to be other than temporary	$ 0	$ 0

Inventories (Schedule of Invent

Inventories (Schedule of Inventories) (Details) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Raw materials	$ 105,026,208	$ 90,780,320
Work-in-process	26,119,390	24,135,944
Finished goods	33,458,465	26,841,620
Total Inventory	$ 164,604,063	$ 141,757,884	[1]
[1]	Note: The condensed consolidated balance sheet at December 31, 2014 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.

Earnings Per Share (Schedule of

Earnings Per Share (Schedule of Earnings Per Share, Basic And Diluted) (Details) - USD ($)	Dec. 05, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Numerators [Abstract]
Numerator for both basic and diluted EPS, net income		$ 78,332,425	$ 72,336,883	$ 230,074,303	$ 217,629,700
Denominators [Abstract]
Denominator for basic EPS, weighted-average shares outstanding		292,589,866	290,969,434	293,742,028	290,383,296
Potentially dilutive shares resulting from stock plans		2,787,612	1,906,518	3,252,544	2,353,616
Denominator for diluted EPS		295,377,478	292,875,952	296,994,572	292,736,912
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive		3,756,369	7,698,848	1,611,900	2,949,114
Common Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Stock split, conversion ratio	2					2
Stock split, stock dividend	100.00%					100.00%

Stock-Based Compensation Plan34

Stock-Based Compensation Plans (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2015USD ($)planshares	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)planshares	Sep. 30, 2014USD ($)	May. 31, 2014shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense for share-based payments	$ 4,404,297	$ 4,778,693	$ 13,979,297	$ 13,391,738
Compensation cost capitalized as part of inventory			279,903
Employee Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (in shares) | shares					24,000,000
Unrecognized compensation cost	$ 22,971,517		$ 22,971,517
Employee Stock Option Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			1 year
Option expiration period			5 years
Employee Stock Option Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			5 years
Option expiration period			7 years
Non-Employee Director Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			6 months
Option expiration period			10 years
Number of shares authorized (in shares) | shares	1,000,000		1,000,000
Unrecognized compensation cost	$ 71,922		$ 71,922
Options granted (in shares) | shares			315,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares approved (in shares) | shares	2,000,000		2,000,000
ESPP discount rate			85.00%
ESPP discount rate recognized as compensation expense			15.00%
Restricted Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares) | shares	9,000,000		9,000,000
Restricted period, maximum, in years			10 years
Unearned stock-based compensation	$ 11,698,198		$ 11,698,198
Amortization expense	$ 905,772		$ 2,555,310
Equity Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans (in plans) | plan	4		4
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans (in plans) | plan	2		2

Stock-Based Compensation Plan35

Stock-Based Compensation Plans (Weighted-Average Assumptions for the ESOP) (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Dividend yield	2.12%	2.36%	2.13%	2.32%
Expected volatility	35.81%	37.70%	36.10%	38.73%
Risk-free interest rate	1.37%	1.79%	1.56%	1.81%
Expected term of options	4 years 113 days	4 years 140 days	4 years 353 days	4 years 307 days
Weighted-avg. grant-date fair value (in dollars per share)	$ 3.94	$ 3.60	$ 4.47	$ 4.13

Comprehensive Income (AOCI Roll

Comprehensive Income (AOCI Rollforward) (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[1]			$ 11,313,015
Comprehensive Income		$ 69,430,897	$ 68,956,915	216,999,662	$ 209,792,103
Balance at end of period		(1,761,626)	14,137,766	(1,761,626)	14,137,766
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		761,692	2,175,183	1,403,899	2,507,922
Other Comprehensive (loss) income before reclassifications		(396,685)	(269,392)	(1,038,892)	(602,131)
Amounts reclassified from accumulated other comprehensive income		0	0	0	0
Comprehensive Income		(396,685)	(269,392)	(1,038,892)	(602,131)
Balance at end of period		365,007	1,905,791	365,007	1,905,791
Unrealized gains on available-for-sale securities:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		8,551,564	15,342,551	10,868,322	19,467,441
Other Comprehensive (loss) income before reclassifications		(6,353,685)	(1,604,338)	(5,727,233)	1,788,502
Amounts reclassified from accumulated other comprehensive income		(1,321,982)	(1,506,238)	(4,265,192)	(9,023,968)
Comprehensive Income		(7,675,667)	(3,110,576)	(9,992,425)	(7,235,466)
Balance at end of period		875,897	12,231,975	875,897	12,231,975
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(2,173,354)	0	(959,206)	0
Other Comprehensive (loss) income before reclassifications		(1,113,648)	0	(2,327,796)	0
Amounts reclassified from accumulated other comprehensive income		284,472	0	284,472	0
Comprehensive Income		(829,176)	0	(2,043,324)	0
Balance at end of period		$ (3,002,530)	$ 0	$ (3,002,530)	$ 0
[1]	Note: The condensed consolidated balance sheet at December 31, 2014 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.

Comprehensive Income (Reclassif

Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	$ (37,715,317)	$ (31,655,724)	$ (104,841,502)	$ (93,677,000)
Amounts Reclassified from Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period	1,037,510	1,506,238	3,980,720	9,023,968
Amounts Reclassified from Other Comprehensive Income | Unrealized gains on available-for-sale securities:
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain on sale of securities	2,033,819	2,317,289	6,561,834	13,883,028
Provision for Income Taxes	(711,837)	(811,051)	(2,296,642)	(4,859,060)
Total reclassifications for the period	1,321,982	1,506,238	4,265,192	9,023,968
Amounts Reclassified from Other Comprehensive Income | Unrealized gains (losses) on derivatives
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain on sale of securities	(437,650)	0	(437,650)	0
Provision for Income Taxes	153,178	0	153,178	0
Total reclassifications for the period	$ (284,472)	$ 0	$ (284,472)	$ 0

Debt and Financing Arrangemen38

Debt and Financing Arrangements (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Oct. 01, 2014	Sep. 27, 2013
Debt Instrument [Line Items]
Long-term debt	$ 227,500,000		$ 227,500,000		$ 258,125,000
Financial Liabilities:
Effect of 1% in increase on borrowing rate	800,000		800,000
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Amount of hedged item						$ 150,000,000
Notional amount of derivative	150,000,000		150,000,000		150,000,000	$ 150,000,000
Fixed interest rate of derivative						1.89%
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Interest Rate Swap Asset	0		0		0
Financial Liabilities:
Interest Rate Swap Liability (Other Accrued Liabilities)	4,619,278		4,619,278		$ 1,475,702
Other, Net [Member]
Debt Instrument [Line Items]
Payments of financing costs	1,300,000	$ 900,000	$ 3,000,000	$ 2,700,000
LIBOR Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			1.19%
Term Loan and Revolving Facility [Member]
Debt Instrument [Line Items]
Partial repayment of debt	26,900,000		$ 30,600,000
Revolving Facility [Member]
Debt Instrument [Line Items]
Partial repayment of debt	25,000,000
Credit Agreement [Member]
Debt Instrument [Line Items]
Additional principal amount available							$ 75,000,000
Revolving Facility [Member]
Debt Instrument [Line Items]
Principal amount							150,000,000
Long-term debt	100,800,000		100,800,000
Available borrowing capacity	49,200,000		49,200,000
Term Loan [Member]
Debt Instrument [Line Items]
Principal amount							150,000,000
Long-term debt	135,000,000		135,000,000
Annual principal repayments	$ 7,500,000		$ 7,500,000
Swing Loans [Member]
Debt Instrument [Line Items]
Additional principal amount available							20,000,000
Letters of Credit [Member]
Debt Instrument [Line Items]
Additional principal amount available							$ 20,000,000

Equity (Details)

Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Aug. 31, 2015	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Equity [Abstract]
Stock repurchased (in shares)					4,885,077
Common stock issued under stock compensation plan (in shares)					1,875,967
Net decrease in period (in shares)					3,009,110
Increase in quarterly cash dividend rate (in dollars per share)		$ 0.005
Dividends declared (in dollars per share)		$ 0.085	$ 0.08	$ 0.08	$ 0.25	$ 0.23
Dividends declared	$ 24.8

Segment Reporting (Schedule Of

Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Revenue	$ 389,829,139	$ 350,913,912	$ 1,138,025,071	$ 1,025,090,220
Income from operations	116,262,620	103,205,827	332,103,956	300,218,811
Automotive Products
Segment Reporting Information [Line Items]
Revenue	379,889,957	341,786,404	1,111,009,546	997,708,190
Income from operations	112,238,938	100,053,622	322,289,461	290,348,056
Other
Segment Reporting Information [Line Items]
Revenue	9,939,182	9,127,508	27,015,525	27,382,030
Income from operations	$ 4,023,682	$ 3,152,205	$ 9,814,495	$ 9,870,755

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Effective income tax rate	32.50%	30.40%
Incremental research and development tax credits			$ 1.8

Stock Split (Details)

Stock Split (Details) - Common Stock - shares	Dec. 05, 2014	Dec. 31, 2014	Dec. 17, 2014
Class of Stock [Line Items]
Stock split, conversion ratio	2	2
Stock split, stock dividend	100.00%	100.00%
Common stock split, additional shares issued for every share held (in shares)			1
Common stock, shares outstanding (in shares)		295,200,000	147,600,000