Gentex (GNTX) 10-Q2 Nov 182018 Q3 Quarterly reportFinancial data

Company Profile

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
Document And Entity Information - shares	Sep. 30, 2018	Oct. 19, 2018
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, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		262,116,951

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Balance Sheets - USD ($)	Sep. 30, 2018	Dec. 31, 2017		Sep. 30, 2017
CURRENT ASSETS
Cash and cash equivalents	$ 194,017,041	$ 569,734,496	[1]	$ 561,999,767
Short-term investments	143,623,541	152,538,054	[1]
Accounts receivable, net	247,322,101	231,121,788	[1]
Inventories	213,394,037	216,765,583	[1]
Prepaid expenses and other	29,201,873	14,403,902	[1]
Total current assets	827,558,593	1,184,563,823	[1]
PLANT AND EQUIPMENT—NET	497,305,597	492,479,330	[1]
OTHER ASSETS
Goodwill	307,365,845	307,365,845	[1]
Long-term investments	141,631,510	57,782,418	[1]
Intangible assets, net	274,500,000	288,975,000	[1]
Patents and other assets, net	21,027,381	20,887,496	[1]
Total other assets	744,524,736	675,010,759	[1]
Total assets	2,069,388,926	2,352,053,912	[1]
CURRENT LIABILITIES
Accounts payable	90,041,982	89,898,467	[1]
Current portion of long-term debt	0	78,000,000	[1]
Accrued liabilities	82,844,508	75,748,540	[1]
Total current liabilities	172,886,490	243,647,007	[1]
DEFERRED INCOME TAXES	53,398,181	58,888,644	[1]
TOTAL LIABILITIES	226,284,671	302,535,651	[1]
SHAREHOLDERS’ INVESTMENT
Common stock	15,727,030	16,816,879	[1]
Additional paid-in capital	743,495,999	723,510,672
Retained earnings	1,086,003,216	1,301,997,327	[1]
Accumulated other comprehensive (loss) income	(2,121,990)	7,193,383	[1]	$ 6,005,415
Total shareholders’ investment	1,843,104,255	2,049,518,261	[1]
Total liabilities and shareholders’ investment	$ 2,069,388,926	$ 2,352,053,912	[1]

[1]	The condensed consolidated balance sheet at December 31, 2017 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 Consolida_2

Unaudited Condensed Consolidated Statements of Income - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
NET SALES	$ 460,253,433	$ 438,627,786	$ 1,380,654,978	$ 1,335,302,109
COST OF GOODS SOLD	287,263,147	267,398,126	862,231,819	821,063,869
Gross profit	172,990,286	171,229,660	518,423,159	514,238,240
OPERATING EXPENSES:
Engineering, research and development	26,888,999	24,770,279	80,138,722	75,165,946
Selling, general & administrative	18,673,376	17,386,729	55,658,189	49,708,008
Total operating expenses	45,562,375	42,157,008	135,796,911	124,873,954
Income from operations	127,427,911	129,072,652	382,626,248	389,364,286
OTHER INCOME (LOSS)
Investment income	3,180,683	2,139,387	8,062,421	5,348,052
Other income (loss), net	(73,979)	(379,996)	578,655	(1,071,628)
Total Other Income	3,106,704	1,759,391	8,641,076	4,276,424
Income before provision for income taxes	130,534,615	130,832,043	391,267,324	393,640,710
PROVISION FOR INCOME TAXES	19,198,798	40,601,708	59,658,782	117,317,687
NET INCOME	$ 111,335,817	$ 90,230,335	$ 331,608,542	$ 276,323,023
EARNINGS PER SHARE:
Basic (in dollars per share)	$ 0.42	$ 0.32	$ 1.23	$ 0.97
Diluted (in dollars per share)	0.42	0.31	1.22	0.96
Cash Dividends Declared per Share (in dollars per share)	$ 0.11	$ 0.10	$ 0.33	$ 0.29

Unaudited Condensed Consolida_3

Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 111,335,817	$ 90,230,335	$ 331,608,542	$ 276,323,023
Other comprehensive income (loss) before tax:
Foreign currency translation adjustments	(1,174,213)	1,182,152	(2,013,638)	2,865,952
Unrealized gains on derivatives	16,165	239,215	98,769	1,376,077
Unrealized (losses) gains on debt securities, net	(609,422)	2,287,103	(932,953)	5,409,722
Other comprehensive (loss) income, before tax	(1,767,470)	3,708,470	(2,847,822)	9,651,751
(Benefit) Expense for income taxes related to components of other comprehensive income (loss)	(124,584)	884,211	(175,177)	2,375,031
Other comprehensive (loss) income, net of tax	(1,642,886)	2,824,259	(2,672,645)	7,276,720
Comprehensive Income	$ 109,692,931	$ 93,054,594	$ 328,935,897	$ 283,599,743

Unaudited Condensed Consolida_4

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 331,608,542		$ 276,323,023
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	80,748,272		74,858,551
Gain on disposal of assets	(145,777)		(163,984)
Loss on disposal of assets	26,839		288,323
Gain on sale of investments	(1,508,411)		(1,028,505)
Loss on sale of investments	532,494		113,091
Deferred income taxes	(5,538,048)		6,855,507
Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock	13,558,557		13,090,804
Change in operating assets and liabilities:
Accounts receivable, net	(16,200,315)		(28,914,071)
Inventories	3,371,546		(17,346,380)
Prepaid expenses and other	(14,797,969)		14,540,408
Accounts payable	143,514		(60,096)
Accrued liabilities, excluding dividends declared and short-term debt	6,408,044		13,999,423
Net cash provided by operating activities	398,207,288		352,556,094
Activity in available-for-sale securities:
Sales proceeds	54,078,232		2,888,493
Maturities and calls	51,892,136		18,100,000
Purchases	(180,657,259)		(18,062,164)
Plant and equipment additions	(68,771,193)		(86,111,836)
Proceeds from sale of plant and equipment	194,200		192,756
Decrease (increase) in other assets	(4,557,125)		2,432,320
Net cash used for investing activities	(147,821,009)		(80,560,431)
CASH FLOWS USED FOR FINANCING ACTIVITIES:
Repayment of debt	(78,000,000)		(78,125,000)
Issuance of common stock from stock plan transactions	61,379,666		31,896,752
Cash dividends paid	(87,733,776)		(80,417,057)
Repurchases of common stock	(521,749,624)		(129,827,666)
Net cash used for financing activities	(626,103,734)		(256,472,971)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(375,717,455)		15,522,692
CASH AND CASH EQUIVALENTS, beginning of period	569,734,496	[1]	546,477,075
CASH AND CASH EQUIVALENTS, end of period	$ 194,017,041		$ 561,999,767

[1]	The condensed consolidated balance sheet at December 31, 2017 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
Basis of Presentation	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of PresentationThe 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 2017 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, 2018, and the results of operations and cash flows for the interim periods presented.

Adoption of New Accounting Pron

Adoption of New Accounting Pronouncements	9 Months Ended
Adoption of New Accounting Pronouncements	Sep. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Adoption of New Accounting Pronouncements	Adoption of New Accounting Pronouncements New Accounting Pronouncements Adopted in Fiscal Year 2018 Effective January 1, 2018, the Company adopted Accounting Standards Codification ("ASC") Topic 606, Revenue from Contracts with Customers , using the modified retrospective method as applied to customer contracts that were not completed as January 1, 2018. As a result, financial information for reporting periods beginning after January 1, 2018 are presented under ASC 606, while comparative financial information has not been adjusted and continues to be reported in accordance with the Company’s historical accounting policy for revenue recognition prior to the adoption of ASC 606. This guidance supersedes 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. In addition, Accounting Standards Update ("ASU") 2014-09 requires certain additional disclosures around the nature, amount, timing, and uncertainty of revenues and cash flows arising from contracts with customers. The Company has documented its accounting policy for the new standard based on a detailed review of its business and contracts. Based on the new guidance, the Company continues to recognize revenue at a particular point in time for the majority of its contracts with customers, which is generally when products are either shipped or delivered, as customer contracts did not meet the criteria in ASC 606 for over-time revenue recognition, specifically the over-time revenue recognition criteria of creating an asset with no alternative use and having an enforceable right to payment for progress towards completion. Therefore, the adoption of ASC 606 did not have a material impact on the consolidated financial statements. The Company has expanded its consolidated financial statement disclosures in order to comply with the disclosure requirements of the ASU. See Note 14 to the Unaudited Condensed Consolidated Financial Statements for additional disclosures regarding the Company’s revenue. Effective January 1, 2018, the Company adopted ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilitie s. The standard amends various aspects of the recognition, measurement, presentation, and disclosure of financial instruments. The most significant impact to the Company's consolidated financial statements relates to the recognition and measurement of equity investments at fair value with changes recognized in net income. The amendment also updates certain presentation and disclosure requirements. The Company had a cumulative-effect adjustment in the first quarter of 2018 of approximately $6.6 million related to the reclassification of the net unrealized gain on available-for-sale securities as of January 1, 2018 from other comprehensive income to retained earnings due to the adoption of this guidance. New Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU 2016-02, Leases , which provides guidance for lease accounting. The new guidance contained in the ASU stipulates that lessees will need to recognize a right-of-use asset and a lease liability for substantially all leases (other than leases that meet the definition of a short-term lease). The liability will be equal to the present value of lease payments. Treatment in the consolidated statements of income will be similar to the current treatment of operating and capital leases. The new guidance is effective on a modified retrospective basis for the Company in the first quarter of its fiscal year ending December 31, 2019. The Company is currently in the process of evaluating the impact of adoption of this standard on its consolidated financial statements, including reviewing all of the available practical expedients for transition. Upon adoption, the Company does not anticipate a material impact on the Company's Consolidated Financial Statements.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
Goodwill and Other Intangible Assets	Sep. 30, 2018
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, 2017 and September 30, 2018 was $307.4 million. In addition to annual impairment testing, which is performed as of the first day of the fourth quarter, 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 tables below: As of September 30, 2018: Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 36,152,904 $ (20,336,961) $ 15,815,943 various Other Intangible Assets HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink® Technology 180,000,000 (75,000,000) 105,000,000 12 years Existing Customer Platforms 43,000,000 (21,500,000) 21,500,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total Other Intangible Assets $ 371,000,000 $ (96,500,000) $ 274,500,000 Total Patents & Other Intangible Assets $ 407,152,904 $ (116,836,961) $ 290,315,943 As of December 31, 2017: Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 34,847,029 $ (18,943,554) $ 15,903,475 various HomeLink® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink® Technology 180,000,000 (63,750,000) 116,250,000 12 years Existing Customer Platforms 43,000,000 (18,275,000) 24,725,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total other identifiable intangible assets $ 371,000,000 $ (82,025,000) $ 288,975,000 Total Patents & Other Intangible Assets $ 405,847,029 $ (100,968,554) $ 304,878,475 Amortization expense on patents and intangible assets was approximately $5.6 million and $16.9 million during the three and nine month periods ended September 30, 2018, respectively, compared to approximately $5.6 million and $16.9 million for the same periods ended September 30, 2017, respectively. Excluding the impact of any future acquisitions, the Company continues to estimate amortization expense for each of the years ended December 31, 2018, 2019, 2020, 2021, and 2022 to be approximately $22 million annually.

Investments

Investments	9 Months Ended
Investments	Sep. 30, 2018
Investments [Abstract]
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 measurement on earnings. The cost of securities sold is based on the specific identification method. The Company’s investments in common stock are stated at fair value based on quoted market prices, and as such are classified as Level 1 assets. The Company determines the fair value of its government securities and corporate bonds by utilizing monthly valuation statements that are provided by its broker. The broker determines the investment valuation by utilizing the bid price in the market and also refers to third party sources to validate valuations, and as such are classified as Level 2 assets. The Company's certificates of deposit have remaining maturities of less than one year and are considered as Level 1 assets. These investments are carried at cost, which approximates fair value. During the year ended December 31, 2017, the Company made technology investments in certain non-consolidated third- parties for ownership interests of less than 20%. These investments do not have readily determinable fair values, and the Company has not identified any observable events that would cause adjustment of the valuation to date, and therefore these investments are held at cost at a total of $3.2 million as of September 30, 2018. These investments are classified within Long-Term Investments in the consolidated balance sheet. Assets or liabilities that have recurring fair value measurements are shown below as of September 30, 2018 and December 31, 2017: As of September 30, 2018 Fair Value Measurements at Reporting Date Using Total as of Quoted Prices in Active Markets for Identical Assets Significant Other Observable Significant Unobservable Inputs Description September 30, 2018 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 194,017,041 $ 194,017,041 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Corporate Bonds 4,994,018 — 4,994,018 — Government Securities 6,691,949 — 6,691,949 — Other 1,937,574 1,937,574 — — Long-Term Investments: Corporate Bonds 62,393,073 — 62,393,073 — Government Securities 58,331,619 — 58,331,619 — Common Stocks 40,000 40,000 — — Municipal Bonds $ 17,666,818 $ 17,666,818 $ — $ — Total $ 476,072,092 $ 343,661,433 $ 132,410,659 $ — As of December 31, 2017 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, 2017 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 569,734,496 $ 569,734,496 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Government Securities 9,011,130 — 9,011,130 — Mutual Funds 393,581 — 393,581 — Corporate Bonds 12,944,999 — 12,944,999 — Other 188,344 188,344 — — Long-Term Investments: Corporate Bonds 3,018,720 — 3,018,720 — Common Stocks 15,703,371 15,703,371 — — Mutual Funds 34,681,337 34,681,337 — — Preferred Stock 1,178,991 1,178,991 — — Total $ 776,854,969 $ 751,486,539 $ 25,368,430 $ — The amortized cost, unrealized gains and losses, and market value of investment securities are shown as of September 30, 2018, and December 31, 2017 As of September 30, 2018: Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities 6,699,555 — (7,606) 6,691,949 Corporate Bonds 4,998,499 — (4,481) 4,994,018 Other 1,937,574 — — 1,937,574 Long-Term Investments: Corporate Bonds 62,619,934 56 (226,917) 62,393,073 Government Securities 58,671,384 — (339,765) 58,331,619 Common Stocks 40,000 — — 40,000 Municipal Bonds 17,841,486 — (174,668) 17,666,818 Total $ 282,808,432 $ 56 $ (753,437) $ 282,055,051 As of December 31, 2017: Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities 9,024,777 — (13,647) 9,011,130 Mutual Funds 392,482 1,575 (476) 393,581 Corporate Bonds 12,952,229 — (7,230) 12,944,999 Other 188,344 — — 188,344 Long-Term Investments: Corporate Bonds 3,022,994 — (4,274) 3,018,720 Common Stocks 10,897,219 5,079,815 (273,663) 15,703,371 Mutual Funds 29,306,540 5,440,344 (65,547) 34,681,337 Preferred Stock 1,141,458 40,533 (3,000) 1,178,991 Total $ 196,926,043 $ 10,562,267 $ (367,837) $ 207,120,473 Unrealized losses on investments as of September 30, 2018, are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 753,437 $ 148,084,928 Greater than one year — — Total $ 753,437 $ 148,084,928 Unrealized losses on investments as of December 31, 2017, are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 263,655 $ 31,223,557 Greater than one year 104,182 285,077 Total $ 367,837 $ 31,508,634 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. No investment losses were considered to be other than temporary during the periods presented. The Company has the intention and current ability to hold its debt investments until the amortized cost basis has been recovered. Fixed income securities as of September 30, 2018 have contractual maturities as follows: Due within one year $ 141,685,968 Due between one and five years 129,595,580 Due over five years 8,795,930 $ 280,077,478

Inventories

Inventories	9 Months Ended
Inventories	Sep. 30, 2018
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consisted of the following at the respective balance sheet dates: September 30, 2018 December 31, 2017 Raw materials $ 134,039,095 $ 139,272,129 Work-in-process 33,336,971 30,481,192 Finished goods 46,017,971 47,012,262 Total Inventory $ 213,394,037 $ 216,765,583

Earnings Per Share

Earnings Per Share	9 Months Ended
Earnings Per Share	Sep. 30, 2018
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): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Numerators: Numerator for both basic and diluted EPS, net income $ 111,335,817 $ 90,230,335 $ 331,608,542 $ 276,323,023 Denominators: Denominator for basic EPS, weighted-average shares outstanding 265,607,128 284,661,920 270,366,996 285,915,565 Potentially dilutive shares resulting from stock plans 1,988,014 2,359,030 2,366,506 3,145,936 Denominator for diluted EPS 267,595,142 287,020,950 272,733,502 289,061,501 Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive 462,631 807,013 24,590 2,847,247

Stock-Based Compensation Plans

Stock-Based Compensation Plans	9 Months Ended
Stock-Based Compensation Plans	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans As of September 30, 2018, 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, 2017, for additional information related to these stock-based compensation plans. The Company recognized compensation expense for share-based payments of $4,829,463 and $13,196,413 for the three and nine months ended September 30, 2018, respectively, and $3,067,076 and $9,957,687 for the three and nine months ended September 30, 2017, respectively. Compensation cost for share based payment awards capitalized as part of inventory as of September 30, 2018 and December 31, 2017 was $224,025 and $279,102, respectively. 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 by allowing them to purchase shares of common stock of the Corporation and thereby having 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, 2018 2017 2018 2017 Dividend Yield (1) 1.99 % 2.10 % 2.09 % 2.15 % Expected volatility (2) 23.32 % 23.09 % 26.65 % 27.68 % Risk-free interest rate (3) 2.94 % 1.92 % 2.78 % 2.00 % Expected term of options (years) (4) 4.19 4.25 4.21 4.17 Weighted-avg. grant date fair value $4.05 $3.35 $4.70 $4.05 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 ten years. As of September 30, 2018, there was $9,600,422 of unrecognized compensation cost related to share-based payments which is expected to be recognized over the remaining 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, 2018, there was $87,458 of unrecognized compensation cost under the non-employee director plan related to share-based payments. The Company has granted options on 480,430 shares under the non-employee director plan through September 30, 2018. 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. As of September 30, 2018, the Company has granted 924,878 shares under this plan. 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 employees of the Company as a means of retaining and rewarding them for 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

Comprehensive Income

Comprehensive Income	9 Months Ended
Comprehensive Income	Sep. 30, 2018
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 debt investments, foreign currency translation adjustments, and derivatives. 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, 2018 2017 2018 2017 Foreign currency translation adjustments: Balance at beginning of period $ (194,395) $ (1,179,199) $ 645,030 $ (2,862,999) Other Comprehensive (loss) income before reclassifications (1,174,213) 1,182,152 (2,013,638) 2,865,952 Net current-period change (1,174,213) 1,182,152 (2,013,638) 2,865,952 Balance at end of period (1,368,608) 2,953 (1,368,608) 2,953 Unrealized gains (losses) on available-for-sale debt securities: Balance at beginning of period (271,939) 4,818,677 (16,349) 2,788,975 Other Comprehensive (loss) income before reclassifications (276,010) 1,371,712 33,941 4,111,338 Amounts reclassified from accumulated other comprehensive income (205,433) 114,905 (770,974) (595,019) Net current-period change (481,443) 1,486,617 (737,033) 3,516,319 Balance at end of period (753,382) 6,305,294 (753,382) 6,305,294 Unrealized gains (losses) on derivatives: Balance at beginning of period (12,770) (458,322) (78,026) (1,197,281) Other comprehensive income (loss) before reclassifications 114,889 424 175,308 124,124 Amounts reclassified from accumulated other comprehensive income (102,119) 155,066 (97,282) 770,325 Net current-period change 12,770 155,490 78,026 894,449 Balance at end of period — (302,832) — (302,832) Accumulated other comprehensive (loss) income, end of period $ (2,121,990) $ 6,005,415 $ (2,121,990) $ 6,005,415 The following table presents details of reclassifications out of accumulated other comprehensive income for the nine months ended September 30, 2018 and 2017. 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, 2018 2017 2018 2017 Unrealized gains (losses) on available-for-sale debt securities Realized gain on sale of securities $ 260,042 $ (176,777) $ 975,917 $ 915,414 Other income (loss), net Provision for income taxes (54,609) 61,872 (204,943) (320,395) Provision for income taxes $ 205,433 $ (114,905) $ 770,974 $ 595,019 Net of tax Unrealized gains (losses) on derivatives Realized gain (loss) on interest rate swap $ 129,265 $ (238,564) $ 123,142 $ (1,185,116) Other income (loss), net Provision for income taxes (27,146) 83,498 (25,860) 414,791 Provision for income taxes $ 102,119 $ (155,066) $ 97,282 $ (770,325) Net of tax Total net reclassifications for the period $ 307,552 $ (269,971) $ 868,256 $ (175,306) Net of tax

Debt and Financing Arrangements

Debt and Financing Arrangements	9 Months Ended
Debt and Financing Arrangements	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt and Financing Arrangements	Debt and Financing Arrangements On September 27, 2013, the Company entered into a credit agreement with certain banks and agents. During the three and nine months ended September 30, 2018, the Company made principal repayments of $23.1 million and $78.0 million, respectively, plus accrued interest, on the previously existing term loan, which completed the repayments on the outstanding balance on the credit facility. The Company used cash and cash equivalents to fund the payments. As of September 30, 2018, there was no outstanding balance on the revolver or the term loan and such credit facility has expired. Interest expense is netted within the "Other, net" section of the Condensed Consolidated Statements of Income , and interest expense associated with the previously existing term loan and revolver was $0.1 million and $0.8 million during the three and nine months ended September 30, 2018, respectively, and $0.7 million and $2.3 million during the three and nine months ended September 30, 2017, respectively. On October 15, 2018, as previously disclosed, the Company entered into a new Credit Agreement (“Credit Agreement”) with PNC as the administrative agent and sole lender. Pursuant to this new Credit Agreement, the Company has access to a $150 million senior revolving credit facility (“Revolver”). Under the terms of the Credit Agreement, the Company is entitled, to further request an additional aggregate principal amount of up to $100 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. As of September 30, 2018, there was no outstanding balance on the Revolver. The Revolver expires on October 15, 2023. The Credit Agreement contains customary representations and warranties and certain covenants that place certain limitations on the Company. As of September 30, 2018, the Company was in compliance with its covenants under the new Credit Agreement.

Equity

Equity	9 Months Ended
Equity	Sep. 30, 2018
Equity [Abstract]
Equity	Equity The decrease in common stock during the nine months ended September 30, 2018, was primarily due to the repurchases of 23.1 million shares, of which 17.6 million shares were acquired pursuant to the Company's previously announced share repurchase plan. In addition, 5.5 million shares were repurchased from the former CEO and subsequently retired, pursuant to his previously disclosed retirement agreement, at a price of $20.98 per share. As previously announced, these share repurchases were separately approved by the Company's Board of Directors and were not repurchased as part of the Company’s existing share repurchase plan. The share repurchases for the first nine months of 2018 were partially offset by the issuance of 4.9 million shares of the Company’s common stock under the Company’s stock-based compensation plans. The total net decrease was 18.2 million shares. The Company announced a $0.01 per share increase in its quarterly cash dividend rate during the first quarter of 2018. As such, the Company recorded a cash dividend of $0.11 during the third quarter of 2018 as compared to a cash dividend of $0.10 per share during the third quarter of 2017. The third quarter 2018 dividend of $28.8 million was declared on August 29, 2018, and was paid on October 17, 2018.

Contingencies

Contingencies	9 Months Ended
Contingencies	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Contingencies	ContingenciesThe 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 or cash flows of the Company.

Segment Reporting

Segment Reporting	9 Months Ended
Segment Reporting	Sep. 30, 2018
Segment Reporting [Abstract]
Segment Reporting	Segment ReportingThe Company's automotive segment develops and manufactures digital vision and connected car products and electronics, including: automatic-dimming rearview mirrors with and without electronic features; non-auto dimming rearview 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, 2018 2017 2018 2017 Revenue: Automotive Products $ 449,184,447 $ 428,161,863 $ 1,348,395,245 $ 1,307,736,698 Other 11,068,986 10,465,923 32,259,733 27,565,411 Total $ 460,253,433 $ 438,627,786 $ 1,380,654,978 $ 1,335,302,109 Income from operations: Automotive Products $ 124,351,499 $ 125,817,994 $ 373,071,852 $ 381,545,762 Other 3,076,412 3,254,658 9,554,396 7,818,524 Total $ 127,427,911 $ 129,072,652 $ 382,626,248 $ 389,364,286

Income Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate was 15.2% in the nine months ended September 30, 2018 compared to 29.8% for the same period in 2017. Generally, effective tax rates for these periods differ from statutory federal income tax rates, due to provisions for state and local income taxes, permanent tax differences, and the foreign-derived intangible income tax deduction during the nine months ended September 30, 2018. The decrease in the effective tax rate for the nine months ended September 30, 2018 compared to the same period of 2017 was due to the reduction of the federal income tax rate from 35% to 21% as a result of the Tax Cuts and Jobs Act ("Act"), as well as R&D tax credits, discrete tax benefits related to equity compensation, and the foreign-derived intangible income tax deduction. Pursuant to the guidance within SEC Staff Accounting Bulletin No. 118 (“SAB 118”), the Company has continued to analyze certain aspects of the Act and refine its application to the Company. Although the Company has not completed its accounting for the income tax effects of certain elements of the Act, during the third quarter of 2018, the Company recorded a total provisional expense of $3.3 million related to the remeasurement of certain deferred tax assets and liabilities. The Company has continued to recognize provisional effects of the Act for which measurement could be reasonably estimated. The ultimate impact of the Act may differ from these estimates due to its continued analysis or further regulatory guidance that may be issued pursuant to the Act. The Company evaluates the impact of the Act as additional clarification and implementation guidance related to the Act is released. Under SAB 118, adjustments to the provisional amounts recorded by the Company as of September 30, 2018 that are identified within a subsequent measurement period of up to one year from the enactment date will be included as an adjustment to tax expense from continuing operations in the period such provisional amounts are actually determined. The Company anticipates the remaining estimates will be finalized in the fourth quarter 2018.

Revenue

Revenue	9 Months Ended
Revenue	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue	RevenueThe following table shows the Company’s Automotive and Other Products revenue disaggregated by geographical location for Automotive Products for the three and Nine month periods ended September 30, 2018: Revenue Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Automotive Products U.S. $ 151,229,829 $ 434,439,455 Germany 81,621,623 259,057,369 Japan 55,363,644 153,843,723 Other 160,969,351 501,054,698 Total Automotive Products $ 449,184,447 $ 1,348,395,245 Other Products (U.S.) 11,068,986 32,259,733 Total Revenue $ 460,253,433 $ 1,380,654,978 Revenue by geographic area may fluctuate based on many factors, including exposure to local economic, political and labor conditions; unexpected changes in laws, regulations, trade or monetary or fiscal policy, including interest rates, foreign currency exchange rates and changes in the rate of inflation in the U.S. and other foreign countries; and tariffs, quotas, customs and other import or export restrictions and other trade barriers. The following table disaggregates the Company’s Automotive and Other revenue by major source for the three and nine month periods ended September 30, 2018: Revenue Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Automotive Segment Automotive Mirrors & Electronics 399,732,577 1,200,521,589 HomeLink Modules* 49,451,870 147,873,656 Total Automotive Products 449,184,447 1,348,395,245 Other Segment Fire Protection Products 5,918,085 17,010,954 Windows Products 5,150,901 15,248,779 Total Other 11,068,986 32,259,733 *Excludes HomeLink revenue related to HomeLink modules integrated into automotive mirrors Revenue is recognized when obligations under the terms of a contract with the customer are satisfied. Such recognition generally occurs with the transfer of control of the products at a point in time. OEM contracts generally include Long Term Supply Agreements ("LTSA") and Purchase Orders ("PO") whereby the LTSA sometimes stipulates the pricing and delivery terms and is evaluated together with a PO, which identifies the quantity, timing, and the type of product to be transferred. Certain customer contracts do not always have an LTSA, in which case, the contracts are governed by the PO from the customer in conjunction with other mutually agreed upon terms and conditions. The Company does not generate revenue from arrangements with multiple deliverables. Revenue is measured as the amount of consideration the Company expects to receive in exchange for transferring goods excluding revenue amounts that are transferred to third parties, such as sales, value add, and other taxes the Company collects concurrently with revenue-producing activities. The Company does not incur any incremental cost to obtain contracts. Costs are incurred to fulfill contracts with the OEM. However, such costs are accounted for under ASC 340-10, and are not treated as fulfillment costs under ASC 340-40. Automotive Products Segment Automotive Rearview Mirrors and Electronics The Company manufactures interior electrochromic automatic-dimming rearview mirrors that darken to reduce glare and improve visibility for the driver. These electronic interior mirrors can also include additional electronic features such as compass, microphones, HomeLink ® , lighting assist and driver assist forward safety camera systems, various lighting systems, various telematics systems, ITM ® systems, and a wide variety of displays. The Company also ships interior non-automatic-dimming rearview mirrors with features. The Company’s interior electrochromic automatic-dimming rearview mirrors also power the application of the Company’s exterior electrochromic automatic-dimming rearview mirrors that darken to reduce glare and improve visibility for the driver. These electronic exterior mirrors typically range in size and shape per automaker specification, but also include additional features such as turn signal indicators, side blind zone indicators, and courtesy lighting. The Company also ships exterior non-automatic-dimming rearview mirrors with similar electronic features as what is available in its automatic-dimming applications. The Company manufactures other automotive electronics products both inside and outside of the rearview mirror through HomeLink ® applications in the vehicle including the rearview mirror, interior visor, overhead console, or center console. For the majority of automotive products, transfer of control and revenue recognition occurs when the Company ships the product from the manufacturing facility to the customer. The Company receives cash equal to the price at the time of invoice for most automotive product sales. For any shipments of product that may be subject to retroactive price adjustments that are then being negotiated, the Company records revenue based on the Company’s best estimate of the amount of consideration to which the entity will be entitled in exchange for transferring the promised goods to the customer. The Company's approach is to consider these adjustments to the contract price as variable consideration which is estimated based on the then most likely price amount. Payment terms on automotive part sales to customers range from 15 days to 90 days. Estimated revenue is adjusted at the earlier of when the most likely amount of consideration expected to be received changes or when the consideration becomes fixed. HomeLink ® Modules The Company manufactures and sells HomeLink ® Modules individually, as well as in combination with the automotive mirrors and other advanced features, as described above. For the majority of automotive products, transfer of control and revenue recognition occurs when the Company ships the product from the manufacturing facility to the customer. Other Segment Dimmable Aircraft Windows The Company supplies variable dimmable windows for the passenger compartment on the Boeing 787 Dreamliner Series of Aircraft. For dimmable aircraft windows, transfer of control and revenue recognition occurs when the Company ships the product from the manufacturing facility to the customer. Payment terms on dimmable aircraft window sales range from 30 days to 45 days. Fire Protection Products

Adoption of New Accounting Pr_2

Adoption of New Accounting Pronouncements (Policies)	9 Months Ended
Adoption of New Accounting Pronouncements (Policies)	Sep. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Adoption of new Accounting Standards	New Accounting Pronouncements Adopted in Fiscal Year 2018 Effective January 1, 2018, the Company adopted Accounting Standards Codification ("ASC") Topic 606, Revenue from Contracts with Customers , using the modified retrospective method as applied to customer contracts that were not completed as January 1, 2018. As a result, financial information for reporting periods beginning after January 1, 2018 are presented under ASC 606, while comparative financial information has not been adjusted and continues to be reported in accordance with the Company’s historical accounting policy for revenue recognition prior to the adoption of ASC 606. This guidance supersedes 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. In addition, Accounting Standards Update ("ASU") 2014-09 requires certain additional disclosures around the nature, amount, timing, and uncertainty of revenues and cash flows arising from contracts with customers. The Company has documented its accounting policy for the new standard based on a detailed review of its business and contracts. Based on the new guidance, the Company continues to recognize revenue at a particular point in time for the majority of its contracts with customers, which is generally when products are either shipped or delivered, as customer contracts did not meet the criteria in ASC 606 for over-time revenue recognition, specifically the over-time revenue recognition criteria of creating an asset with no alternative use and having an enforceable right to payment for progress towards completion. Therefore, the adoption of ASC 606 did not have a material impact on the consolidated financial statements. The Company has expanded its consolidated financial statement disclosures in order to comply with the disclosure requirements of the ASU. See Note 14 to the Unaudited Condensed Consolidated Financial Statements for additional disclosures regarding the Company’s revenue. Effective January 1, 2018, the Company adopted ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilitie s. The standard amends various aspects of the recognition, measurement, presentation, and disclosure of financial instruments. The most significant impact to the Company's consolidated financial statements relates to the recognition and measurement of equity investments at fair value with changes recognized in net income. The amendment also updates certain presentation and disclosure requirements. The Company had a cumulative-effect adjustment in the first quarter of 2018 of approximately $6.6 million related to the reclassification of the net unrealized gain on available-for-sale securities as of January 1, 2018 from other comprehensive income to retained earnings due to the adoption of this guidance. New Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU 2016-02, Leases , which provides guidance for lease accounting. The new guidance contained in the ASU stipulates that lessees will need to recognize a right-of-use asset and a lease liability for substantially all leases (other than leases that meet the definition of a short-term lease). The liability will be equal to the present value of lease payments. Treatment in the consolidated statements of income will be similar to the current treatment of operating and capital leases. The new guidance is effective on a modified retrospective basis for the Company in the first quarter of its fiscal year ending December 31, 2019. The Company is currently in the process of evaluating the impact of adoption of this standard on its consolidated financial statements, including reviewing all of the available practical expedients for transition. Upon adoption, the Company does not anticipate a material impact on the Company's Consolidated Financial Statements.

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
Goodwill and Other Intangible Assets (Tables)	Sep. 30, 2018
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 tables below: As of September 30, 2018: Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 36,152,904 $ (20,336,961) $ 15,815,943 various Other Intangible Assets HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink® Technology 180,000,000 (75,000,000) 105,000,000 12 years Existing Customer Platforms 43,000,000 (21,500,000) 21,500,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total Other Intangible Assets $ 371,000,000 $ (96,500,000) $ 274,500,000 Total Patents & Other Intangible Assets $ 407,152,904 $ (116,836,961) $ 290,315,943 As of December 31, 2017: Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 34,847,029 $ (18,943,554) $ 15,903,475 various HomeLink® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink® Technology 180,000,000 (63,750,000) 116,250,000 12 years Existing Customer Platforms 43,000,000 (18,275,000) 24,725,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total other identifiable intangible assets $ 371,000,000 $ (82,025,000) $ 288,975,000 Total Patents & Other Intangible Assets $ 405,847,029 $ (100,968,554) $ 304,878,475

Investments (Tables)

Investments (Tables)	9 Months Ended
Investments (Tables)	Sep. 30, 2018
Investments [Abstract]
Investment Securities Stated at Fair Value	Assets or liabilities that have recurring fair value measurements are shown below as of September 30, 2018 and December 31, 2017: As of September 30, 2018 Fair Value Measurements at Reporting Date Using Total as of Quoted Prices in Active Markets for Identical Assets Significant Other Observable Significant Unobservable Inputs Description September 30, 2018 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 194,017,041 $ 194,017,041 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Corporate Bonds 4,994,018 — 4,994,018 — Government Securities 6,691,949 — 6,691,949 — Other 1,937,574 1,937,574 — — Long-Term Investments: Corporate Bonds 62,393,073 — 62,393,073 — Government Securities 58,331,619 — 58,331,619 — Common Stocks 40,000 40,000 — — Municipal Bonds $ 17,666,818 $ 17,666,818 $ — $ — Total $ 476,072,092 $ 343,661,433 $ 132,410,659 $ — As of December 31, 2017 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, 2017 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 569,734,496 $ 569,734,496 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Government Securities 9,011,130 — 9,011,130 — Mutual Funds 393,581 — 393,581 — Corporate Bonds 12,944,999 — 12,944,999 — Other 188,344 188,344 — — Long-Term Investments: Corporate Bonds 3,018,720 — 3,018,720 — Common Stocks 15,703,371 15,703,371 — — Mutual Funds 34,681,337 34,681,337 — — Preferred Stock 1,178,991 1,178,991 — — Total $ 776,854,969 $ 751,486,539 $ 25,368,430 $ —
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, 2018, and December 31, 2017 As of September 30, 2018: Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities 6,699,555 — (7,606) 6,691,949 Corporate Bonds 4,998,499 — (4,481) 4,994,018 Other 1,937,574 — — 1,937,574 Long-Term Investments: Corporate Bonds 62,619,934 56 (226,917) 62,393,073 Government Securities 58,671,384 — (339,765) 58,331,619 Common Stocks 40,000 — — 40,000 Municipal Bonds 17,841,486 — (174,668) 17,666,818 Total $ 282,808,432 $ 56 $ (753,437) $ 282,055,051 As of December 31, 2017: Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities 9,024,777 — (13,647) 9,011,130 Mutual Funds 392,482 1,575 (476) 393,581 Corporate Bonds 12,952,229 — (7,230) 12,944,999 Other 188,344 — — 188,344 Long-Term Investments: Corporate Bonds 3,022,994 — (4,274) 3,018,720 Common Stocks 10,897,219 5,079,815 (273,663) 15,703,371 Mutual Funds 29,306,540 5,440,344 (65,547) 34,681,337 Preferred Stock 1,141,458 40,533 (3,000) 1,178,991 Total $ 196,926,043 $ 10,562,267 $ (367,837) $ 207,120,473
Schedule of Unrealized Loss on Investments	Unrealized losses on investments as of September 30, 2018, are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 753,437 $ 148,084,928 Greater than one year — — Total $ 753,437 $ 148,084,928 Unrealized losses on investments as of December 31, 2017, are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 263,655 $ 31,223,557 Greater than one year 104,182 285,077 Total $ 367,837 $ 31,508,634
Investments Classified by Contractual Maturity Date	Fixed income securities as of September 30, 2018 have contractual maturities as follows: Due within one year $ 141,685,968 Due between one and five years 129,595,580 Due over five years 8,795,930 $ 280,077,478

Inventories (Tables)

Inventories (Tables)	9 Months Ended
Inventories (Tables)	Sep. 30, 2018
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories consisted of the following at the respective balance sheet dates: September 30, 2018 December 31, 2017 Raw materials $ 134,039,095 $ 139,272,129 Work-in-process 33,336,971 30,481,192 Finished goods 46,017,971 47,012,262 Total Inventory $ 213,394,037 $ 216,765,583

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
Earnings Per Share (Tables)	Sep. 30, 2018
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): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Numerators: Numerator for both basic and diluted EPS, net income $ 111,335,817 $ 90,230,335 $ 331,608,542 $ 276,323,023 Denominators: Denominator for basic EPS, weighted-average shares outstanding 265,607,128 284,661,920 270,366,996 285,915,565 Potentially dilutive shares resulting from stock plans 1,988,014 2,359,030 2,366,506 3,145,936 Denominator for diluted EPS 267,595,142 287,020,950 272,733,502 289,061,501 Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive 462,631 807,013 24,590 2,847,247

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	9 Months Ended
Stock-Based Compensation Plans (Tables)	Sep. 30, 2018
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, 2018 2017 2018 2017 Dividend Yield (1) 1.99 % 2.10 % 2.09 % 2.15 % Expected volatility (2) 23.32 % 23.09 % 26.65 % 27.68 % Risk-free interest rate (3) 2.94 % 1.92 % 2.78 % 2.00 % Expected term of options (years) (4) 4.19 4.25 4.21 4.17 Weighted-avg. grant date fair value $4.05 $3.35 $4.70 $4.05 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
Comprehensive Income (Tables)	Sep. 30, 2018
Equity [Abstract]
Schedule of AOCI	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, 2018 2017 2018 2017 Foreign currency translation adjustments: Balance at beginning of period $ (194,395) $ (1,179,199) $ 645,030 $ (2,862,999) Other Comprehensive (loss) income before reclassifications (1,174,213) 1,182,152 (2,013,638) 2,865,952 Net current-period change (1,174,213) 1,182,152 (2,013,638) 2,865,952 Balance at end of period (1,368,608) 2,953 (1,368,608) 2,953 Unrealized gains (losses) on available-for-sale debt securities: Balance at beginning of period (271,939) 4,818,677 (16,349) 2,788,975 Other Comprehensive (loss) income before reclassifications (276,010) 1,371,712 33,941 4,111,338 Amounts reclassified from accumulated other comprehensive income (205,433) 114,905 (770,974) (595,019) Net current-period change (481,443) 1,486,617 (737,033) 3,516,319 Balance at end of period (753,382) 6,305,294 (753,382) 6,305,294 Unrealized gains (losses) on derivatives: Balance at beginning of period (12,770) (458,322) (78,026) (1,197,281) Other comprehensive income (loss) before reclassifications 114,889 424 175,308 124,124 Amounts reclassified from accumulated other comprehensive income (102,119) 155,066 (97,282) 770,325 Net current-period change 12,770 155,490 78,026 894,449 Balance at end of period — (302,832) — (302,832) Accumulated other comprehensive (loss) income, end of period $ (2,121,990) $ 6,005,415 $ (2,121,990) $ 6,005,415
Reclassifications out of other comprehensive income	The following table presents details of reclassifications out of accumulated other comprehensive income for the nine months ended September 30, 2018 and 2017. 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, 2018 2017 2018 2017 Unrealized gains (losses) on available-for-sale debt securities Realized gain on sale of securities $ 260,042 $ (176,777) $ 975,917 $ 915,414 Other income (loss), net Provision for income taxes (54,609) 61,872 (204,943) (320,395) Provision for income taxes $ 205,433 $ (114,905) $ 770,974 $ 595,019 Net of tax Unrealized gains (losses) on derivatives Realized gain (loss) on interest rate swap $ 129,265 $ (238,564) $ 123,142 $ (1,185,116) Other income (loss), net Provision for income taxes (27,146) 83,498 (25,860) 414,791 Provision for income taxes $ 102,119 $ (155,066) $ 97,282 $ (770,325) Net of tax Total net reclassifications for the period $ 307,552 $ (269,971) $ 868,256 $ (175,306) Net of tax

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
Segment Reporting (Tables)	Sep. 30, 2018
Segment Reporting [Abstract]
Schedule of Automotive and Other Segment Reporting	The Company's automotive segment develops and manufactures digital vision and connected car products and electronics, including: automatic-dimming rearview mirrors with and without electronic features; non-auto dimming rearview 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, 2018 2017 2018 2017 Revenue: Automotive Products $ 449,184,447 $ 428,161,863 $ 1,348,395,245 $ 1,307,736,698 Other 11,068,986 10,465,923 32,259,733 27,565,411 Total $ 460,253,433 $ 438,627,786 $ 1,380,654,978 $ 1,335,302,109 Income from operations: Automotive Products $ 124,351,499 $ 125,817,994 $ 373,071,852 $ 381,545,762 Other 3,076,412 3,254,658 9,554,396 7,818,524 Total $ 127,427,911 $ 129,072,652 $ 382,626,248 $ 389,364,286

Revenue (Tables)

Revenue (Tables)	9 Months Ended
Revenue (Tables)	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table shows the Company’s Automotive and Other Products revenue disaggregated by geographical location for Automotive Products for the three and Nine month periods ended September 30, 2018: Revenue Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Automotive Products U.S. $ 151,229,829 $ 434,439,455 Germany 81,621,623 259,057,369 Japan 55,363,644 153,843,723 Other 160,969,351 501,054,698 Total Automotive Products $ 449,184,447 $ 1,348,395,245 Other Products (U.S.) 11,068,986 32,259,733 Total Revenue $ 460,253,433 $ 1,380,654,978 Revenue by geographic area may fluctuate based on many factors, including exposure to local economic, political and labor conditions; unexpected changes in laws, regulations, trade or monetary or fiscal policy, including interest rates, foreign currency exchange rates and changes in the rate of inflation in the U.S. and other foreign countries; and tariffs, quotas, customs and other import or export restrictions and other trade barriers. The following table disaggregates the Company’s Automotive and Other revenue by major source for the three and nine month periods ended September 30, 2018: Revenue Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Automotive Segment Automotive Mirrors & Electronics 399,732,577 1,200,521,589 HomeLink Modules* 49,451,870 147,873,656 Total Automotive Products 449,184,447 1,348,395,245 Other Segment Fire Protection Products 5,918,085 17,010,954 Windows Products 5,150,901 15,248,779 Total Other 11,068,986 32,259,733 *Excludes HomeLink revenue related to HomeLink modules integrated into automotive mirrors

Adoption of New Accounting Pr_3

Adoption of New Accounting Pronouncements (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment	$ 6.6

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	[1]	Sep. 27, 2013
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 307,365,845		$ 307,365,845		$ 307,365,845
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
Amortization expense, 2022	22,000,000		22,000,000
HomeLink®
Finite-Lived Intangible Assets [Line Items]
Goodwill							$ 307,400,000
Gentex Patents
Finite-Lived Intangible Assets [Line Items]
Amortization expense	5,600,000	$ 5,600,000	5,600,000	$ 5,600,000
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 16,900,000	$ 16,900,000	$ 16,900,000	$ 16,900,000

[1]	The condensed consolidated balance sheet at December 31, 2017 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 Intangible_4

Goodwill and Other Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	$ (96,500,000)	$ (82,025,000)
Intangible assets, gross	371,000,000	371,000,000
Intangible assets, net	274,500,000	288,975,000	[1]
Gentex Patents
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	36,152,904	34,847,029
Finite-lived intangible assets, accumulated amortization	(20,336,961)	(18,943,554)
Finite-lived intangible assets, net	15,815,943	15,903,475
Homelink Technology
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	180,000,000	180,000,000
Finite-lived intangible assets, accumulated amortization	(75,000,000)	(63,750,000)
Finite-lived intangible assets, net	$ 105,000,000	$ 116,250,000
Finite-lived intangible asset, useful life	12 years	12 years
Existing Customer Platforms
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 43,000,000	$ 43,000,000
Finite-lived intangible assets, accumulated amortization	(21,500,000)	(18,275,000)
Finite-lived intangible assets, net	$ 21,500,000	$ 24,725,000
Finite-lived intangible asset, useful life	10 years	10 years
Patents and Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	$ (116,836,961)	$ (100,968,554)
Intangible assets, gross	407,152,904	405,847,029
Intangible assets, net	290,315,943	304,878,475
HomeLink Trade Names and Trademarks
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	52,000,000	52,000,000
Exclusive Licensing Agreement
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 96,000,000	$ 96,000,000

[1]	The condensed consolidated balance sheet at December 31, 2017 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 (Narrative) (Detail

Investments (Narrative) (Details) - USD ($)	3 Months Ended			9 Months Ended		12 Months Ended
Investments (Narrative) (Details) - USD ($)	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Technology investments in non-consolidated affiliates (less than)						20.00%
Technology investments in non-consolidated affiliates	$ 3,200,000			$ 3,200,000
Equity investment losses were considered to be other than temporary	$ 0		$ 0	$ 0	$ 0	$ 0
Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment		$ 6,600,000

Investments (Schedule of Assets

Investments (Schedule of Assets or Liabilities, Recurring Fair Value Measurements) (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	$ 194,017,041	$ 569,734,496
Market Value	282,055,051	207,120,473
Investments and Cash	476,072,092	776,854,969
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	194,017,041	569,734,496
Investments and Cash	343,661,433	751,486,539
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	0	0
Investments and Cash	132,410,659	25,368,430
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	0	0
Investments and Cash	0	0
Short-Term Investments \| Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	130,000,000	130,000,000
Short-Term Investments \| Certificates of Deposit \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	130,000,000	130,000,000
Short-Term Investments \| Certificates of Deposit \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Short-Term Investments \| Certificates of Deposit \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Short-Term Investments \| Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	4,994,018	12,944,999
Short-Term Investments \| Corporate Bonds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Short-Term Investments \| Corporate Bonds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	4,994,018	12,944,999
Short-Term Investments \| Corporate Bonds \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Short-Term Investments \| Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	6,691,949	9,011,130
Short-Term Investments \| Government Securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Short-Term Investments \| Government Securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	6,691,949	9,011,130
Short-Term Investments \| Government Securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Short-Term Investments \| Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		393,581
Short-Term Investments \| Mutual Funds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		0
Short-Term Investments \| Mutual Funds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		393,581
Short-Term Investments \| Mutual Funds \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		0
Short-Term Investments \| Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	1,937,574	188,344
Short-Term Investments \| Other \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	1,937,574	188,344
Short-Term Investments \| Other \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Short-Term Investments \| Other \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Long-Term Investments \| Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	62,393,073	3,018,720
Long-Term Investments \| Corporate Bonds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Long-Term Investments \| Corporate Bonds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	62,393,073	3,018,720
Long-Term Investments \| Corporate Bonds \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Long-Term Investments \| Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	58,331,619
Long-Term Investments \| Government Securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0
Long-Term Investments \| Government Securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	58,331,619
Long-Term Investments \| Government Securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0
Long-Term Investments \| Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		34,681,337
Long-Term Investments \| Mutual Funds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		34,681,337
Long-Term Investments \| Mutual Funds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		0
Long-Term Investments \| Mutual Funds \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		0
Long-Term Investments \| Common Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	40,000	15,703,371
Long-Term Investments \| Common Stocks \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	40,000	15,703,371
Long-Term Investments \| Common Stocks \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Long-Term Investments \| Common Stocks \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Long-Term Investments \| Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	17,666,818
Long-Term Investments \| Municipal Bonds [Member] \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	17,666,818
Long-Term Investments \| Municipal Bonds [Member] \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0
Long-Term Investments \| Municipal Bonds [Member] \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0
Long-Term Investments \| Preferred Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	$ 17,666,818	1,178,991
Long-Term Investments \| Preferred Stock \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		1,178,991
Long-Term Investments \| Preferred Stock \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		0
Long-Term Investments \| Preferred Stock \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		$ 0

Investments (Schedule of Amorti

Investments (Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value of Investment Securities) (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Cost	$ 282,808,432	$ 196,926,043
Unrealized Gains	56	10,562,267
Unrealized Losses	(753,437)	(367,837)
Market Value	282,055,051	207,120,473
Short-Term Investments \| Certificates of Deposit
Debt Securities, Available-for-sale [Line Items]
Cost	130,000,000	130,000,000
Unrealized Gains	0	0
Unrealized Losses	0	0
Market Value	130,000,000	130,000,000
Short-Term Investments \| Corporate Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	4,998,499	12,952,229
Unrealized Gains	0	0
Unrealized Losses	(4,481)	(7,230)
Market Value	4,994,018	12,944,999
Short-Term Investments \| Government Securities
Debt Securities, Available-for-sale [Line Items]
Cost	6,699,555	9,024,777
Unrealized Gains	0	0
Unrealized Losses	(7,606)	(13,647)
Market Value	6,691,949	9,011,130
Short-Term Investments \| Mutual Funds
Debt Securities, Available-for-sale [Line Items]
Cost		392,482
Unrealized Gains		1,575
Unrealized Losses		(476)
Market Value		393,581
Short-Term Investments \| Other
Debt Securities, Available-for-sale [Line Items]
Cost	1,937,574	188,344
Unrealized Gains	0	0
Unrealized Losses	0	0
Market Value	1,937,574	188,344
Long-Term Investments \| Corporate Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	62,619,934	3,022,994
Unrealized Gains	56	0
Unrealized Losses	(226,917)	(4,274)
Market Value	62,393,073	3,018,720
Long-Term Investments \| Government Securities
Debt Securities, Available-for-sale [Line Items]
Cost	58,671,384
Unrealized Gains	0
Unrealized Losses	(339,765)
Market Value	58,331,619
Long-Term Investments \| Mutual Funds
Debt Securities, Available-for-sale [Line Items]
Cost		29,306,540
Unrealized Gains		5,440,344
Unrealized Losses		(65,547)
Market Value		34,681,337
Long-Term Investments \| Common Stocks
Debt Securities, Available-for-sale [Line Items]
Cost	40,000	10,897,219
Unrealized Gains	0	5,079,815
Unrealized Losses	0	(273,663)
Market Value	40,000	15,703,371
Long-Term Investments \| Preferred Stock
Debt Securities, Available-for-sale [Line Items]
Cost	17,841,486	1,141,458
Unrealized Gains	0	40,533
Unrealized Losses	(174,668)	(3,000)
Market Value	$ 17,666,818	$ 1,178,991

Investments (Schedule of Unreal

Investments (Schedule of Unrealized Loss on Investments) (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Investments [Abstract]
Aggregate Unrealized Losses, Less than one year	$ 753,437	$ 263,655
Aggregate Fair Value, Less than one year	148,084,928	31,223,557
Aggregate Unrealized Losses, Greater than one year	0	104,182
Aggregate Fair Value, Greater than one year	0	285,077
Aggregate Unrealized Losses, Total	753,437	367,837
Aggregate Fair Value, Total	$ 148,084,928	$ 31,508,634

Investments (Investments Classi

Investments (Investments Classified by Contractual Maturity Date) (Details) - Fixed Income Securities	Sep. 30, 2018USD ($)
Debt Securities, Available-for-sale [Line Items]
Due within one year	$ 141,685,968
Due between one and five years	129,595,580
Due over five years	8,795,930
Total	$ 280,077,478

Inventories (Schedule of Invent

Inventories (Schedule of Inventories) (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 134,039,095	$ 139,272,129
Work-in-process	33,336,971	30,481,192
Finished goods	46,017,971	47,012,262
Total Inventory	$ 213,394,037	$ 216,765,583	[1]

[1]	The condensed consolidated balance sheet at December 31, 2017 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 ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerators:
Numerator for both basic and diluted EPS, net income	$ 111,335,817	$ 90,230,335	$ 331,608,542	$ 276,323,023
Denominators:
Denominator for basic EPS, weighted-average shares outstanding (in shares)	265,607,128	284,661,920	270,366,996	285,915,565
Potentially dilutive shares resulting from stock plans (in shares)	1,988,014	2,359,030	2,366,506	3,145,936
Denominator for diluted EPS (in shares)	267,595,142	287,020,950	272,733,502	289,061,501
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive (in shares)	462,631	807,013	24,590	2,847,247

Stock-Based Compensation Plan_2

Stock-Based Compensation Plans (Narrative) (Details)	3 Months Ended		9 Months Ended
Stock-Based Compensation Plans (Narrative) (Details)	Sep. 30, 2018USD ($)planshares	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)planshares	Sep. 30, 2017USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense for share-based payments \| $	$ 4,829,463	$ 3,067,076	$ 13,196,413	$ 9,957,687
Compensation cost capitalized as part of inventory \| $			$ 224,025	279,102
Employee Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (in shares) \| shares	24,000,000		24,000,000
Unrecognized compensation cost \| $	$ 9,600,422		$ 9,600,422
Employee Stock Option Plan \| Minimum
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 \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			5 years
Option expiration period			10 years
Non Employee Director Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			6 months
Option expiration period			10 years
Unrecognized compensation cost \| $	$ 87,458		$ 87,458
Number of shares authorized (in shares) \| shares	1,000,000		1,000,000
Options granted (in shares) \| shares			480,430
Employee Stock Purchase Plan
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%
Shares granted (in shares) \| shares	924,878		924,878
Restricted Stock Plan
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 \| $	$ 33,559,239		$ 33,559,239
Amortization expense \| $	$ 2,480,911	$ 1,788,162	$ 6,314,544	$ 4,014,820
Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans \| plan	4		4
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans \| plan	2		2

Stock-Based Compensation Plan_3

Stock-Based Compensation Plans (Weighted-Average Assumptions for the ESOP) (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Dividend yield	1.99%	2.10%	2.09%	2.15%
Expected volatility	23.32%	23.09%	26.65%	27.68%
Risk-free interest rate	2.94%	1.92%	2.78%	2.00%
Expected term of options	4 years 2 months 8 days	4 years 3 months	4 years 2 months 15 days	4 years 2 months 1 day
Weighted-avg. grant-date fair value (in dollars per share)	$ 4.05	$ 3.35	$ 4.70	$ 4.05

Comprehensive Income (AOCI Roll

Comprehensive Income (AOCI Rollforward) (Details) - USD ($)		3 Months Ended		9 Months Ended
Comprehensive Income (AOCI Rollforward) (Details) - USD ($)		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[1]			$ 2,049,518,261
Comprehensive Income		$ 109,692,931	$ 93,054,594	328,935,897	$ 283,599,743
Balance at end of period		1,843,104,255		1,843,104,255
Accumulated other comprehensive income (loss), end of period
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at end of period		(2,121,990)	6,005,415	(2,121,990)	6,005,415
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(194,395)	(1,179,199)	645,030	(2,862,999)
Other Comprehensive income (loss) before reclassifications		(1,174,213)	1,182,152	(2,013,638)	2,865,952
Comprehensive Income		(1,174,213)	1,182,152	(2,013,638)	2,865,952
Balance at end of period		(1,368,608)	2,953	(1,368,608)	2,953
Unrealized gains (losses) on available-for-sale debt securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(271,939)	4,818,677	(16,349)	2,788,975
Other Comprehensive income (loss) before reclassifications		(276,010)	1,371,712	33,941	4,111,338
Amounts reclassified from accumulated other comprehensive income		(205,433)	114,905	(770,974)	(595,019)
Comprehensive Income		(481,443)	1,486,617	(737,033)	3,516,319
Balance at end of period		(753,382)	6,305,294	(753,382)	6,305,294
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(12,770)	(458,322)	(78,026)	(1,197,281)
Other Comprehensive income (loss) before reclassifications		114,889	424	175,308	124,124
Amounts reclassified from accumulated other comprehensive income		(102,119)	155,066	(97,282)	770,325
Comprehensive Income		12,770	155,490	78,026	894,449
Balance at end of period		$ 0	$ (302,832)	$ 0	$ (302,832)

[1]	The condensed consolidated balance sheet at December 31, 2017 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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes	$ (19,198,798)	$ (40,601,708)	$ (59,658,782)	$ (117,317,687)
Amounts Reclassified from Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total net reclassifications for the period	307,552	(269,971)	868,256	(175,306)
Amounts Reclassified from Other Comprehensive Income \| Unrealized gains (losses) on available-for-sale debt securities
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss) on sale of securities and interest rate swap	260,042	(176,777)	975,917	915,414
Provision for income taxes	(54,609)	61,872	(204,943)	(320,395)
Total net reclassifications for the period	205,433	(114,905)	770,974	595,019
Amounts Reclassified from Other Comprehensive Income \| Unrealized gains (losses) on derivatives
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss) on sale of securities and interest rate swap	129,265	(238,564)	123,142	(1,185,116)
Provision for income taxes	(27,146)	83,498	(25,860)	414,791
Total net reclassifications for the period	$ 102,119	$ (155,066)	$ 97,282	$ (770,325)

Debt and Financing Arrangemen_2

Debt and Financing Arrangements (Details) - USD ($)	3 Months Ended		9 Months Ended
Debt and Financing Arrangements (Details) - USD ($)	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Oct. 15, 2018
Other, Net
Debt Instrument [Line Items]
Payments of financing costs	$ 100,000	$ 800,000	$ 700,000	$ 2,300,000
Term Loan and Revolving Facility
Debt Instrument [Line Items]
Partial repayment of debt	23,100,000		78,000,000
Term Loan and Revolving Facility
Debt Instrument [Line Items]
Long-term debt	0		0
Revolving Facility
Debt Instrument [Line Items]
Long-term debt	$ 0		$ 0
Subsequent Event \| Revolving Facility
Debt Instrument [Line Items]
Principal amount					$ 150,000,000
Subsequent Event \| Credit Agreement
Debt Instrument [Line Items]
Additional borrowings available					100,000,000
Subsequent Event \| Swing Loans
Debt Instrument [Line Items]
Additional borrowings available					20,000,000
Subsequent Event \| Letter of Credit
Debt Instrument [Line Items]
Additional borrowings available					$ 20,000,000

Equity (Details)

Equity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Equity [Abstract]
Stock repurchased (in shares)				23.1		17.6
Stock repurchased and retired (in shares)				5.5
Stock repurchased and retired (in dollars per share)				$ 20.98
Common stock issued under stock compensation plan (in shares)				4.9
Net decrease in period (in shares)				18.2
Increase in quarterly dividend rate (in dollars per share)		$ 0.01
Dividends declared (in dollars per share)	$ 0.11		$ 0.10	$ 0.33	$ 0.29
Dividends declared	$ 28.8

Segment Reporting (Schedule Of

Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenue	$ 460,253,433	$ 438,627,786	$ 1,380,654,978	$ 1,335,302,109
Income from operations	127,427,911	129,072,652	382,626,248	389,364,286
Automotive Products
Segment Reporting Information [Line Items]
Revenue	449,184,447	428,161,863	1,348,395,245	1,307,736,698
Income from operations	124,351,499	125,817,994	373,071,852	381,545,762
Other
Segment Reporting Information [Line Items]
Revenue	11,068,986	10,465,923	32,259,733	27,565,411
Income from operations	$ 3,076,412	$ 3,254,658	$ 9,554,396	$ 7,818,524

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate		15.20%	29.80%
Provisional expense	$ 3.3

Revenue (Details)

Revenue (Details) - USD ($)	3 Months Ended		9 Months Ended
Revenue (Details) - USD ($)	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 460,253,433	$ 438,627,786	$ 1,380,654,978	$ 1,335,302,109
Automotive Segment
Disaggregation of Revenue [Line Items]
Revenue	449,184,447		1,348,395,245
Other Segment
Disaggregation of Revenue [Line Items]
Revenue	11,068,986		32,259,733
Automotive Products
Disaggregation of Revenue [Line Items]
Revenue	449,184,447		1,348,395,245
Automotive Mirrors & Electronics \| Automotive Segment
Disaggregation of Revenue [Line Items]
Revenue	399,732,577		$ 1,200,521,589
Automotive Mirrors & Electronics \| Automotive Segment \| Minimum
Disaggregation of Revenue [Line Items]
Payment terms			15 days
Automotive Mirrors & Electronics \| Automotive Segment \| Maximum
Disaggregation of Revenue [Line Items]
Payment terms			90 days
HomeLink Modules \| Automotive Segment
Disaggregation of Revenue [Line Items]
Revenue	49,451,870		$ 147,873,656
Fire Protection Products \| Other Segment
Disaggregation of Revenue [Line Items]
Revenue	5,918,085		$ 17,010,954
Fire Protection Products \| Other Segment \| Minimum
Disaggregation of Revenue [Line Items]
Payment terms			30 days
Fire Protection Products \| Other Segment \| Maximum
Disaggregation of Revenue [Line Items]
Payment terms			75 days
Windows Products \| Other Segment
Disaggregation of Revenue [Line Items]
Revenue	5,150,901		$ 15,248,779
Dimmable Aircraft Windows \| Other Segment \| Minimum
Disaggregation of Revenue [Line Items]
Payment terms			30 days
Dimmable Aircraft Windows \| Other Segment \| Maximum
Disaggregation of Revenue [Line Items]
Payment terms			45 days
U.S. \| Automotive Products
Disaggregation of Revenue [Line Items]
Revenue	151,229,829		$ 434,439,455
U.S. \| Other Products
Disaggregation of Revenue [Line Items]
Revenue	11,068,986		32,259,733
Germany \| Automotive Products
Disaggregation of Revenue [Line Items]
Revenue	81,621,623		259,057,369
Japan \| Automotive Products
Disaggregation of Revenue [Line Items]
Revenue	55,363,644		153,843,723
Other \| Automotive Products
Disaggregation of Revenue [Line Items]
Revenue	$ 160,969,351		$ 501,054,698