Gentex (GNTX) 10-Q 4 May 18 2018 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 20, 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	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		273,854,076

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2018	Dec. 31, 2017
CURRENT ASSETS
Cash and cash equivalents	$ 524,323,560	$ 569,734,496	[1]
Short-term investments	152,179,408	152,538,054	[1]
Accounts receivable, net	246,427,239	231,121,788	[1]
Inventories	207,232,952	216,765,583	[1]
Prepaid expenses and other	11,531,029	14,403,902	[1]
Total current assets	1,141,694,188	1,184,563,823	[1]
PLANT AND EQUIPMENT—NET	496,274,467	492,479,330	[1]
OTHER ASSETS
Goodwill	307,365,845	307,365,845	[1]
Long-term investments	3,240,000	57,782,418	[1]
Intangible Assets, net	284,150,000	288,975,000	[1]
Patents and other assets, net	21,627,968	20,887,496	[1]
Total other assets	616,383,813	675,010,759	[1]
Total assets	2,254,352,468	2,352,053,912	[1]
CURRENT LIABILITIES
Accounts payable	77,307,897	89,898,467	[1]
Current portion of long-term debt	50,000,000	78,000,000
Accrued liabilities	100,861,709	75,748,540
Total current liabilities	228,169,606	243,647,007	[1]
DEFERRED INCOME TAXES	56,205,366	58,888,644	[1]
TOTAL LIABILITIES	284,374,972	302,535,651	[1]
SHAREHOLDERS’ INVESTMENT
Common stock	16,431,263	16,816,879	[1]
Additional paid-in capital	742,491,728	723,510,672	[1]
Retained earnings	1,208,841,516	1,301,997,327	[1]
Accumulated other comprehensive income	2,212,989	7,193,383	[1]
Total shareholders’ investment	1,969,977,496	2,049,518,261	[1]
Total liabilities and shareholders’ investment	$ 2,254,352,468	$ 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 Consolidat3

Unaudited Condensed Consolidated Statements of Income - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
NET SALES	$ 465,420,105	$ 453,535,250
COST OF GOODS SOLD	292,791,704	277,734,465
Gross profit	172,628,401	175,800,785
OPERATING EXPENSES:
Engineering, research and development	26,049,258	25,152,257
Selling, general & administrative	18,063,810	16,221,408
Total operating expenses	44,113,068	41,373,665
Income from operations	128,515,333	134,427,120
OTHER INCOME (LOSS)
Investment income	2,037,605	1,472,527
Other Income (Loss), net	1,206,993	(1,034,743)
Total Other Income	3,244,598	437,784
Income before provision for income taxes	131,759,931	134,864,904
PROVISION FOR INCOME TAXES	20,511,188	37,308,163
NET INCOME	$ 111,248,743	$ 97,556,741
EARNINGS PER SHARE:
Basic (in dollars per share)	$ 0.40	$ 0.34
Diluted (in dollars per share)	0.40	0.33
Cash Dividends Declared per Share (in dollars per share)	$ 0.110	$ 0.09

Unaudited Condensed Consolidat4

Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 111,248,743	$ 97,556,741
Other comprehensive income (loss) before tax:
Foreign currency translation adjustments	1,626,178	188,590
Unrealized gains on derivatives	67,047	641,975
Unrealized gains (losses) on debt securities, net	(21,280)	2,170,254
Other comprehensive income, before tax	1,671,945	3,000,819
Expense for income taxes related to components of other comprehensive income	9,611	984,280
Other comprehensive income, net of tax	1,662,334	2,016,539
Comprehensive Income	$ 112,911,077	$ 99,573,280

Unaudited Condensed Consolidat5

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($)		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income		$ 111,248,743	$ 97,556,741
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		28,046,434	25,181,854
Gain on disposal of assets		(4,374)	(146,261)
Loss on disposal of assets		8,677	359,959
Gain on sale of investments		(1,245,075)	(274,844)
Loss on sale of investments		529,484	21,431
Deferred income taxes		(2,746,797)	5,718,363
Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock		3,977,471	4,422,996
Change in operating assets and liabilities:
Accounts receivable, net		(15,305,451)	(37,866,173)
Inventories		9,532,631	(7,776,814)
Prepaid expenses and other		2,872,873	18,857,501
Accounts payable		(12,590,570)	(2,249,350)
Accrued liabilities, excluding dividends declared and short-term debt		23,125,002	27,385,768
Net cash provided by operating activities		147,449,048	131,191,171
Activity in available-for-sale securities:
Sales proceeds		53,822,052	1,316,280
Maturities and calls		3,000,000	6,100,000
Purchases		(1,213,405)	(16,225,018)
Plant and equipment additions		(26,247,890)	(27,119,993)
Proceeds from sale of plant and equipment		67,400	15,001
Decrease (Increase) in other assets		45,322	(588,361)
Net cash provided by (used for) investing activities		29,473,479	(36,502,091)
CASH FLOWS USED FOR FINANCING ACTIVITIES:
Repayment of debt		(28,000,000)	(41,875,000)
Issuance of common stock from stock plan transactions		36,267,047	17,237,232
Cash dividends paid		(28,028,132)	(25,896,377)
Repurchases of common stock		(202,572,378)	(30,986,385)
Net cash used for financing activities		(222,333,463)	(81,520,530)
NET INCREASE IN CASH AND CASH EQUIVALENTS		(45,410,936)	13,168,550
CASH AND CASH EQUIVALENTS, beginning of period	[1]	569,734,496
CASH AND CASH EQUIVALENTS, end of period		$ 524,323,560	$ 559,645,625
[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	3 Months Ended
	Mar. 31, 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 March 31, 2018, and the results of operations and cash flows for the interim period presented.

Adoption of New Accounting Pron

Adoption of New Accounting Pronouncements	3 Months Ended
	Mar. 31, 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 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, 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 implementation 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 earnings 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. 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	3 Months Ended
	Mar. 31, 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 March 31, 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 March 31, 2018: Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 36,352,536 $ (19,760,899) $ 16,591,637 various Other Intangible Assets HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (67,500,000) 112,500,000 12 years Existing Customer Platforms 43,000,000 (19,350,000) 23,650,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total Other Intangible Assets $ 371,000,000 $ (86,850,000) $ 284,150,000 Total Patents & Other Intangible Assets $ 407,352,536 $ (106,610,899) $ 300,741,637 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 $5.7 million during the three month period ended March 31, 2018, compared to approximately $5.6 million for the same period ended March 31, 2017. 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	3 Months Ended
	Mar. 31, 2018
Investments [Abstract]
Investments	Investments The Company follows the provisions of ASC 820, “Fair Value Measurements and Disclosures” for its financial assets and liabilities, and for its non-financial assets and liabilities subject to fair value measurements. ASC 820 provides a framework for measuring the fair value of assets and liabilities. This framework is intended to provide increased consistency in how fair value determinations are made under various existing accounting standards that permit, or in some cases, require estimates of fair-market value. This standard also expanded financial statement disclosure requirements about a company’s use of fair-value measurements, including the effect of such measurement on earnings. The cost of securities sold is based on the specific identification method. 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 on the Company's consolidated financial statements relates to the recognition and measurement of equity investments at fair value with changes recognized in net income, though there are also updates to certain presentation and disclosures. 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 as a result of the implementation of this guidance. 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 affiliates for ownership interests of less than 20%. These investments do not have readily determinable fair values, and the Company has not to date identified any observable events that would cause adjustment, and therefore these investments are held at cost at a total of $3.2 million as of March 31, 2018. These investments are classified within Long-Term Investments in the consolidated balance sheet. Long-term investments decreased from December 31, 2017 to March 31, 2018 as a result of the sale of the majority of the Company's available-for-sale equity investments as part of its previously announced capital allocation strategy. Assets or liabilities that have recurring fair value measurements are shown below as of March 31, 2018 and December 31, 2017: As of March 31, 2018: 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 March 31, 2018 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 524,323,560 $ 524,323,560 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Corporate Bonds 15,891,817 — 15,891,817 — Government Securities 6,003,510 — 6,003,510 — Other 284,081 284,081 — — Long-Term Investments: Common Stocks 40,000 40,000 — — Total $ 676,542,968 $ 654,647,641 $ 21,895,327 $ — 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 March 31, 2018, and December 31, 2017: As of March 31, 2018: Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities 6,009,310 — (5,800) 6,003,510 Corporate Bonds 15,919,177 — (27,360) 15,891,817 Other 284,081 — — 284,081 Long-Term Investments: Common Stocks 40,000 — — 40,000 Total $ 152,252,568 $ — $ (33,160) $ 152,219,408 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 March 31, 2018, are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 33,160 $ 21,895,327 Greater than one year — — Total $ 33,160 $ 21,895,327 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 March 31, 2018 have contractual maturities as follows: Due within one year $ 151,895,327 Due between one and five years — Due over five years — $ 151,895,327

Inventories

Inventories	3 Months Ended
	Mar. 31, 2018
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consisted of the following at the respective balance sheet dates: March 31, 2018 December 31, 2017 Raw materials $ 132,138,376 $ 139,272,129 Work-in-process 31,124,313 30,481,192 Finished goods 43,970,263 47,012,262 Total Inventory $ 207,232,952 $ 216,765,583

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 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 March 31, 2018 2017 Numerators: Numerator for both basic and diluted EPS, net income $ 111,248,743 $ 97,556,741 Denominators: Denominator for basic EPS, weighted-average shares outstanding 274,759,516 287,408,900 Potentially dilutive shares resulting from stock plans 2,749,912 4,070,938 Denominator for diluted EPS 277,509,428 291,479,838 Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive 156,467 2,311

Stock-Based Compensation Plans

Stock-Based Compensation Plans	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans As of March 31, 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 $3,901,316 for the three months ended March 31, 2018, and $3,484,240 for the three months ended March 31, 2017. Compensation cost for share based payment awards capitalized as part of inventory as of March 31, 2018 and March 31, 2017 was $258,651 and $226,119, 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 and allow them to purchase shares of common stock of the Corporation and thereby have an additional incentive to contribute to the prosperity of the Company. The fair value of each option grant in the employee stock option plan was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions for the indicated periods: Three Months Ended March 31, 2018 2017 Dividend Yield (1) 2.02 % 2.18 % Expected volatility (2) 23.26 % 29.81 % Risk-free interest rate (3) 2.56 % 2.10 % Expected term of options (years) (4) 4.19 4.09 Weighted-avg. grant date fair value $4.18 $4.51 Represents the Company’s estimated cash dividend yield over the expected term of option grant. 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. Represents the U.S. Treasury yield over the expected term of the option grant. 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 five 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 March 31, 2018, there was no unrecognized compensation cost under the non-employee director plan related to share-based payments. The Company has granted options on 427,000 shares under the non-employee director plan through March 31, 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 March 31, 2018, the Company has granted 824,647 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 ownership except that the shares may not be sold, transferred, pledged, exchanged or otherwise disposed of during the restriction period. The restriction period is determined by the Compensation Committee, appointed by the Board of Directors, but may not exceed ten years under the terms of the plan. As of March 31, 2018, the Company had unearned stock-based compensation of $27,760,004 associated with these restricted stock grants. The unearned stock-based compensation related to these grants is being amortized to compensation expense over the applicable restriction periods. Amortization expense from restricted stock grants in the three months ended March 31, 2018 and 2017 was $1,643,060 and $940,811, respectively.

Comprehensive Income

Comprehensive Income	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Comprehensive Income	Comprehensive IncomeComprehensive income reflects the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. For the Company, comprehensive income represents net income adjusted for unrealized gains and losses on certain investments, 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 March 31, 2018 2017 Foreign currency translation adjustments: Balance at beginning of period $ 645,030 $ (2,862,999) Other Comprehensive income before reclassifications 1,626,178 188,590 Net current-period change 1,626,178 188,590 Balance at end of period 2,271,208 (2,674,409) Unrealized gains (losses) on available-for-sale debt securities: Balance at beginning of period (16,349) 2,788,975 Other Comprehensive income before reclassifications 548,506 1,575,383 Amounts reclassified from accumulated other comprehensive income (565,317) (164,718) Net current-period change (16,811) 1,410,665 Balance at end of period (33,160) 4,199,640 Unrealized gains (losses) on derivatives: Balance at beginning of period (78,026) (1,197,281) Other comprehensive income before reclassifications 43,173 147,318 Amounts reclassified from accumulated other comprehensive income 9,794 269,966 Net current-period change 52,967 417,284 Balance at end of period (25,059) (779,997) Accumulated other comprehensive income, end of period $ 2,212,989 $ 745,234 The following table presents details of reclassifications out of accumulated other comprehensive income for the three months ended March 31, 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 March 31, 2018 2017 Unrealized gains (losses) on available-for-sale securities Realized gain on sale of securities $ 715,591 $ 253,413 Other income (loss), net Provision for income taxes (150,274) (88,695) Provision for income taxes $ 565,317 $ 164,718 Net of tax Unrealized gains (losses) on derivatives Realized loss on interest rate swap $ (12,398) $ (415,333) Other income (loss), net Provision for income taxes 2,604 145,367 Provision for income taxes $ (9,794) $ (269,966) Net of tax Total net reclassifications for the period $ 555,523 $ (105,248) Net of tax

Debt and Financing Arrangements

Debt and Financing Arrangements	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Debt and Financing Arrangements	Debt and Financing Arrangements On September 27, 2013, the Company entered into a Credit Agreement (“Credit Agreement”) with certain banks and agents. Pursuant to the Credit Agreement, the Company is the borrower under a $150 million senior revolving credit facility (“Revolver”) and a $150 million term loan facility (“Term Loan”). Under the terms of the Credit Agreement, the Company is entitled, to further request an additional aggregate principal amount of up to $75 million, subject to the satisfaction of certain conditions. In addition, the Company is entitled to the benefit of swing loans from amounts otherwise available under the Revolver in the aggregate principal amount of up to $20 million and to request Letters of Credit from amounts otherwise available under the Revolver in the aggregate principle amount up to $20 million, both subject to certain conditions. The obligations of the Company under the Credit Agreement are not secured, but are subject to certain covenants. The Revolver expires and the Term Loan matures on September 27, 2018. During the three months ended March 31, 2018, the Company made principal repayments of $28.0 million, plus accrued interest, on the Term Loan and Revolver. The aforementioned payments include a payment made by the Company of $26.1 million on the Term Loan during the first quarter of 2018, which was in addition to scheduled amounts due. The Company used cash and cash equivalents to fund the payments. As of March 31, 2018, there was no outstanding balance on the Revolver. Under current terms of the Term Loan, the Company is required to make principal repayments of $7.5 million annually. As of March 31, 2018, $50.0 million was outstanding under the Term Loan. As of March 31, 2018, the borrowing rate on both its Term Loan and Revolver are derived from the one month LIBOR, and based on the Company's leverage ratio as of March 31, 2018 the interest rate on its borrowings is equal to 2.88%. Interest expense is netted within the "Other, net" section of the Condensed Consolidated Statements of Income, and interest expense associated with the Term Loan and Revolver was $0.5 million during the three months ended March 31, 2018, and $0.9 million during the three months ended March 31, 2017, respectively. The Credit Agreement contains customary representations and warranties and certain covenants that place certain limitations on the Company. As of March 31, 2018, the Company was in compliance with its covenants under the Credit Agreement.

Equity

Equity	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Equity	Equity The decrease in common stock during the three months ended March 31, 2018, was primarily due to the repurchases of 9.3 million shares, of which 3.8 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 in the first quarter of 2018 were partially offset by the issuance of 2.9 million shares of the Company’s common stock under the Company’s stock-based compensation plans. The total net decrease was 6.4 million shares. The Company announced a $0.01 per share increase in its quarterly cash dividend rate during the second quarter of 2017, and a further $0.01 per share increase during the first quarter of 2018. As such, the Company recorded a cash dividend of $0.11 during the first quarter of 2018 as compared to a cash dividend of $0.09 per share during the first quarter of 2017. The first quarter 2018 dividend of $30.1 million, was declared on March 9, 2018, and was paid on April 18, 2018.

Contingencies

Contingencies	3 Months Ended
	Mar. 31, 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	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company's automotive segment develops and manufactures electro-optic 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 March 31, 2018 2017 Revenue: Automotive Products $ 454,965,374 $ 445,652,575 Other 10,454,731 7,882,675 Total $ 465,420,105 $ 453,535,250 Income from operations: Automotive Products $ 124,962,159 $ 132,504,957 Other 3,553,174 1,922,163 Total $ 128,515,333 $ 134,427,120

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate was 15.6% in the three months ended March 31, 2018 compared to 27.7% 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 three month period ended March 31, 2018. The decrease in the effective tax rate for the three months ended March 31, 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”), as the Company has continued to analyze certain aspects of the Act and refine its application to the Company. 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. Under SAB 118, adjustments to the provisional amounts recorded by the Company as of March 31, 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 the amounts are determined.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	Revenue The Company adopted ASC 606 using the modified retrospective method as applied to customer contracts that were not completed as of 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 and then applicable guidance for revenue recognition prior to the adoption of ASC 606. The following table shows the Company’s Automotive and Other Products revenue disaggregated by geographical location for Automotive Products for the period ended March 31, 2018: Revenue Three Months Ended March 31, 2018 Automotive Products U.S. 140,312,987 Germany 91,793,541 Japan 49,832,997 Other 173,025,849 Total Automotive Products 454,965,374 Other Products (U.S.) 10,454,731 Total Revenue 465,420,105 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 period ended March 31, 2018: Revenue Three Months Ended March 31, 2018 Automotive Segment Automotive Mirrors & Electronics 404,241,628 HomeLink Modules* 50,723,746 Total Automotive Products 454,965,374 Other Segment Fire Protection Products 5,279,658 Windows Products 5,175,073 Total Other 10,454,731 *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 and excludes from revenue amounts which 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 invoice price for most automotive product sales at time of invoice. 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 to customers range from 30 days to 45 days. Fire Protection Products

Adoption of New Accounting Pr20

Adoption of New Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Adoption of new Accounting Standards	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 implementation 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 earnings 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. Upon adoption, the Company does not anticipate a material impact on the Company's Consolidated Financial Statements.

Goodwill and Other Intangible21

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2018: Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 36,352,536 $ (19,760,899) $ 16,591,637 various Other Intangible Assets HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (67,500,000) 112,500,000 12 years Existing Customer Platforms 43,000,000 (19,350,000) 23,650,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total Other Intangible Assets $ 371,000,000 $ (86,850,000) $ 284,150,000 Total Patents & Other Intangible Assets $ 407,352,536 $ (106,610,899) $ 300,741,637 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)	3 Months Ended
	Mar. 31, 2018
Investments [Abstract]
Investment Securities Stated at Fair Value	As of March 31, 2018: 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 March 31, 2018 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 524,323,560 $ 524,323,560 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Corporate Bonds 15,891,817 — 15,891,817 — Government Securities 6,003,510 — 6,003,510 — Other 284,081 284,081 — — Long-Term Investments: Common Stocks 40,000 40,000 — — Total $ 676,542,968 $ 654,647,641 $ 21,895,327 $ — 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	As of March 31, 2018: Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities 6,009,310 — (5,800) 6,003,510 Corporate Bonds 15,919,177 — (27,360) 15,891,817 Other 284,081 — — 284,081 Long-Term Investments: Common Stocks 40,000 — — 40,000 Total $ 152,252,568 $ — $ (33,160) $ 152,219,408 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 March 31, 2018, are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 33,160 $ 21,895,327 Greater than one year — — Total $ 33,160 $ 21,895,327 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 March 31, 2018 have contractual maturities as follows: Due within one year $ 151,895,327 Due between one and five years — Due over five years — $ 151,895,327

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2018
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories consisted of the following at the respective balance sheet dates: March 31, 2018 December 31, 2017 Raw materials $ 132,138,376 $ 139,272,129 Work-in-process 31,124,313 30,481,192 Finished goods 43,970,263 47,012,262 Total Inventory $ 207,232,952 $ 216,765,583

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2018 2017 Numerators: Numerator for both basic and diluted EPS, net income $ 111,248,743 $ 97,556,741 Denominators: Denominator for basic EPS, weighted-average shares outstanding 274,759,516 287,408,900 Potentially dilutive shares resulting from stock plans 2,749,912 4,070,938 Denominator for diluted EPS 277,509,428 291,479,838 Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive 156,467 2,311

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2018 2017 Dividend Yield (1) 2.02 % 2.18 % Expected volatility (2) 23.26 % 29.81 % Risk-free interest rate (3) 2.56 % 2.10 % Expected term of options (years) (4) 4.19 4.09 Weighted-avg. grant date fair value $4.18 $4.51 Represents the Company’s estimated cash dividend yield over the expected term of option grant. 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. Represents the U.S. Treasury yield over the expected term of the option grant. 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)	3 Months Ended
	Mar. 31, 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 March 31, 2018 2017 Foreign currency translation adjustments: Balance at beginning of period $ 645,030 $ (2,862,999) Other Comprehensive income before reclassifications 1,626,178 188,590 Net current-period change 1,626,178 188,590 Balance at end of period 2,271,208 (2,674,409) Unrealized gains (losses) on available-for-sale debt securities: Balance at beginning of period (16,349) 2,788,975 Other Comprehensive income before reclassifications 548,506 1,575,383 Amounts reclassified from accumulated other comprehensive income (565,317) (164,718) Net current-period change (16,811) 1,410,665 Balance at end of period (33,160) 4,199,640 Unrealized gains (losses) on derivatives: Balance at beginning of period (78,026) (1,197,281) Other comprehensive income before reclassifications 43,173 147,318 Amounts reclassified from accumulated other comprehensive income 9,794 269,966 Net current-period change 52,967 417,284 Balance at end of period (25,059) (779,997) Accumulated other comprehensive income, end of period $ 2,212,989 $ 745,234
Reclassifications out of other comprehensive income	The following table presents details of reclassifications out of accumulated other comprehensive income for the three months ended March 31, 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 March 31, 2018 2017 Unrealized gains (losses) on available-for-sale securities Realized gain on sale of securities $ 715,591 $ 253,413 Other income (loss), net Provision for income taxes (150,274) (88,695) Provision for income taxes $ 565,317 $ 164,718 Net of tax Unrealized gains (losses) on derivatives Realized loss on interest rate swap $ (12,398) $ (415,333) Other income (loss), net Provision for income taxes 2,604 145,367 Provision for income taxes $ (9,794) $ (269,966) Net of tax Total net reclassifications for the period $ 555,523 $ (105,248) Net of tax

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Schedule of Automotive and Other Segment Reporting	The Company also develops and manufactures variably dimming windows for the aerospace industry and fire protection products for the commercial construction industry, which are combined into the "Other" segment shown below. Three Months Ended March 31, 2018 2017 Revenue: Automotive Products $ 454,965,374 $ 445,652,575 Other 10,454,731 7,882,675 Total $ 465,420,105 $ 453,535,250 Income from operations: Automotive Products $ 124,962,159 $ 132,504,957 Other 3,553,174 1,922,163 Total $ 128,515,333 $ 134,427,120

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 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 period ended March 31, 2018: Revenue Three Months Ended March 31, 2018 Automotive Products U.S. 140,312,987 Germany 91,793,541 Japan 49,832,997 Other 173,025,849 Total Automotive Products 454,965,374 Other Products (U.S.) 10,454,731 Total Revenue 465,420,105 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 period ended March 31, 2018: Revenue Three Months Ended March 31, 2018 Automotive Segment Automotive Mirrors & Electronics 404,241,628 HomeLink Modules* 50,723,746 Total Automotive Products 454,965,374 Other Segment Fire Protection Products 5,279,658 Windows Products 5,175,073 Total Other 10,454,731 *Excludes HomeLink revenue related to HomeLink modules integrated into automotive mirrors

Adoption of New Accounting Pr29

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 Intangible30

Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	[1]	Sep. 27, 2013
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 307,365,845		$ 307,365,845
Amortization expense, 2018	22,000,000
Amortization expense, 2019	22,000,000
Amortization expense, 2020	22,000,000
Amortization expense, 2021	22,000,000
Amortization expense, 2022	22,000,000
HomeLink®
Finite-Lived Intangible Assets [Line Items]
Goodwill					$ 307,400,000
Patents and Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 5,700,000	$ 5,600,000
[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 Intangible31

Goodwill and Other Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	$ (86,850,000)	$ (82,025,000)
Intangible assets, gross	371,000,000	371,000,000
Intangible assets, net	284,150,000	288,975,000	[1]
Gentex Patents
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	36,352,536	34,847,029
Finite-lived intangible assets, accumulated amortization	(19,760,899)	(18,943,554)
Finite-lived intangible assets, net	16,591,637	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	(67,500,000)	(63,750,000)
Finite-lived intangible assets, net	$ 112,500,000	$ 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	(19,350,000)	(18,275,000)
Finite-lived intangible assets, net	$ 23,650,000	$ 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	$ (106,610,899)	$ (100,968,554)
Intangible assets, gross	407,352,536	405,847,029
Intangible assets, net	300,741,637	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		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity investment losses were considered to be other than temporary	$ 0	$ 0
Technology investments in non-consolidated affiliates (less than)			20.00%
Technology investments in non-consolidated affiliates	3,200,000
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 ($)	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	$ 524,323,560	$ 569,734,496
Market Value	152,219,408	207,120,473
Investments and Cash	676,542,968	776,854,969
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	524,323,560	569,734,496
Investments and Cash	654,647,641	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	21,895,327	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	15,891,817	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	15,891,817	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	6,003,510	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	6,003,510	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	284,081	188,344
Short-Term Investments | Other | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	284,081	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		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
Long-Term Investments | Corporate Bonds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		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
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 | Preferred Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value		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 ($)	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 152,252,568	$ 196,926,043
Unrealized Gains	0	10,562,267
Unrealized Losses	(33,160)	(367,837)
Market Value	152,219,408	207,120,473
Short-Term Investments | Certificates of Deposit
Schedule of Available-for-sale Securities [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
Schedule of Available-for-sale Securities [Line Items]
Cost	15,919,177	12,952,229
Unrealized Gains	0	0
Unrealized Losses	(27,360)	(7,230)
Market Value	15,891,817	12,944,999
Short-Term Investments | Government Securities
Schedule of Available-for-sale Securities [Line Items]
Cost	6,009,310	9,024,777
Unrealized Gains	0	0
Unrealized Losses	(5,800)	(13,647)
Market Value	6,003,510	9,011,130
Short-Term Investments | Mutual Funds
Schedule of Available-for-sale Securities [Line Items]
Cost		392,482
Unrealized Gains		1,575
Unrealized Losses		(476)
Market Value		393,581
Short-Term Investments | Other
Schedule of Available-for-sale Securities [Line Items]
Cost	284,081	188,344
Unrealized Gains	0	0
Unrealized Losses	0	0
Market Value	284,081	188,344
Long-Term Investments | Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Cost		3,022,994
Unrealized Gains		0
Unrealized Losses		(4,274)
Market Value		3,018,720
Long-Term Investments | Mutual Funds
Schedule of Available-for-sale Securities [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
Schedule of Available-for-sale Securities [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
Schedule of Available-for-sale Securities [Line Items]
Cost		1,141,458
Unrealized Gains		40,533
Unrealized Losses		(3,000)
Market Value		$ 1,178,991

Investments (Schedule of Unreal

Investments (Schedule of Unrealized Loss on Investments) (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Investments [Abstract]
Aggregate Unrealized Losses, Less than one year	$ 33,160	$ 263,655
Aggregate Fair Value, Less than one year	21,895,327	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	33,160	367,837
Aggregate Fair Value, Total	$ 21,895,327	$ 31,508,634

Investments (Investments Classi

Investments (Investments Classified by Contractual Maturity Date) (Details) - Fixed Income Securities	Mar. 31, 2018USD ($)
Schedule of Available-for-sale Securities [Line Items]
Due within one year	$ 151,895,327
Due between one and five years	0
Due over five years	0
Total	$ 151,895,327

Inventories (Schedule of Invent

Inventories (Schedule of Inventories) (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 132,138,376	$ 139,272,129
Work-in-process	31,124,313	30,481,192
Finished goods	43,970,263	47,012,262
Total Inventory	$ 207,232,952	$ 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
	Mar. 31, 2018	Mar. 31, 2017
Numerators:
Numerator for both basic and diluted EPS, net income	$ 111,248,743	$ 97,556,741
Denominators:
Denominator for basic EPS, weighted-average shares outstanding (in shares)	274,759,516	287,408,900
Potentially dilutive shares resulting from stock plans (in shares)	2,749,912	4,070,938
Denominator for diluted EPS (in shares)	277,509,428	291,479,838
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive (in shares)	156,467	2,311

Stock-Based Compensation Plan39

Stock-Based Compensation Plans (Narrative) (Details)	3 Months Ended
	Mar. 31, 2018USD ($)planshares	Mar. 31, 2017USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense for share-based payments | $	$ 3,901,316	$ 3,484,240
Compensation cost capitalized as part of inventory | $	$ 258,651	226,119
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
Unrecognized compensation cost | $	$ 10,686,587
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 expiration period	10 years
Unrecognized compensation cost | $	$ 0
Number of shares authorized (in shares) | shares	1,000,000
Options granted (in shares) | shares	427,000
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares approved (in shares) | shares	2,000,000
ESPP discount rate	85.00%
ESPP discount rate recognized as compensation expense	15.00%
Shares granted (in shares) | shares	824,647
Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares) | shares	9,000,000
Restricted period, maximum, in years	10 years
Unearned stock-based compensation | $	$ 27,760,004
Amortization expense | $	$ 1,643,060	$ 940,811
Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans | plan	4
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans | plan	2

Stock-Based Compensation Plan40

Stock-Based Compensation Plans (Weighted-Average Assumptions for the ESOP) (Details) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Dividend yield	2.02%	2.18%
Expected volatility	23.26%	29.81%
Risk-free interest rate	2.56%	2.10%
Expected term of options	4 years 2 months 8 days	4 years 1 month 2 days
Weighted-avg. grant-date fair value (in dollars per share)	$ 4.18	$ 4.51

Comprehensive Income (AOCI Roll

Comprehensive Income (AOCI Rollforward) (Details) - USD ($)		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[1]	$ 2,049,518,261
Comprehensive Income		112,911,077	$ 99,573,280
Balance at end of period		1,969,977,496
Accumulated other comprehensive income (loss), end of period
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at end of period		2,212,989	745,234
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		645,030	(2,862,999)
Other Comprehensive income (loss) before reclassifications		1,626,178	188,590
Comprehensive Income		1,626,178	188,590
Balance at end of period		2,271,208	(2,674,409)
Unrealized gains (losses) on available-for-sale debt securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(16,349)	2,788,975
Other Comprehensive income (loss) before reclassifications		548,506	1,575,383
Amounts reclassified from accumulated other comprehensive income		(565,317)	(164,718)
Comprehensive Income		(16,811)	1,410,665
Balance at end of period		(33,160)	4,199,640
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(78,026)	(1,197,281)
Other Comprehensive income (loss) before reclassifications		43,173	147,318
Amounts reclassified from accumulated other comprehensive income		9,794	269,966
Comprehensive Income		52,967	417,284
Balance at end of period		$ (25,059)	$ (779,997)
[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
	Mar. 31, 2018	Mar. 31, 2017
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes	$ (20,511,188)	$ (37,308,163)
Amounts Reclassified from Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total net reclassifications for the period	555,523	(105,248)
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	715,591	253,413
Provision for income taxes	(150,274)	(88,695)
Total net reclassifications for the period	565,317	164,718
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	(12,398)	(415,333)
Provision for income taxes	2,604	145,367
Total net reclassifications for the period	$ (9,794)	$ (269,966)

Debt and Financing Arrangemen43

Debt and Financing Arrangements (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Sep. 27, 2013
Other, Net
Debt Instrument [Line Items]
Payments of financing costs	$ 500,000	$ 900,000
LIBOR Rate
Debt Instrument [Line Items]
Basis spread on variable rate	2.88%
Term Loan
Debt Instrument [Line Items]
Partial repayment of debt	$ 26,100,000
Term Loan and Revolving Facility
Debt Instrument [Line Items]
Partial repayment of debt	28,000,000
Credit Agreement
Debt Instrument [Line Items]
Additional borrowings available			$ 75,000,000
Revolving Facility
Debt Instrument [Line Items]
Principal amount			150,000,000
Long-term debt	0
Term Loan
Debt Instrument [Line Items]
Principal amount			150,000,000
Long-term debt	50,000,000
Annual principal repayments	$ 7,500,000
Swing Loans
Debt Instrument [Line Items]
Additional borrowings available			20,000,000
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
	Mar. 31, 2018	Jun. 30, 2017	Mar. 31, 2017
Equity [Abstract]
Stock repurchased (in shares)	9.3
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)	2.9
Net decrease in period (in shares)	6.4
Increase in quarterly dividend rate (in dollars per share)	$ 0.01	$ 0.01
Dividends declared (in dollars per share)	$ 0.110		$ 0.09
Dividends declared	$ 30.1

Segment Reporting (Schedule Of

Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 465,420,105	$ 453,535,250
Income from operations	128,515,333	134,427,120
Automotive Products
Segment Reporting Information [Line Items]
Revenue	454,965,374	445,652,575
Income from operations	124,962,159	132,504,957
Other
Segment Reporting Information [Line Items]
Revenue	10,454,731	7,882,675
Income from operations	$ 3,553,174	$ 1,922,163

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate	15.60%	27.70%

Revenue (Details)

Revenue (Details)	3 Months Ended
	Mar. 31, 2018USD ($)
Disaggregation of Revenue [Line Items]
Total revenue	$ 465,420,105
Automotive Segment
Disaggregation of Revenue [Line Items]
Total revenue	454,965,374
Other Segment
Disaggregation of Revenue [Line Items]
Total revenue	10,454,731
Automotive Products
Disaggregation of Revenue [Line Items]
Total revenue	454,965,374
Automotive Mirrors & Electronics | Automotive Segment
Disaggregation of Revenue [Line Items]
Total revenue	$ 404,241,628
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]
Total revenue	$ 50,723,746
Fire Protection Products | Other Segment
Disaggregation of Revenue [Line Items]
Total revenue	$ 5,279,658
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]
Total revenue	$ 5,175,073
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]
Total revenue	$ 140,312,987
U.S. | Other Products
Disaggregation of Revenue [Line Items]
Total revenue	10,454,731
Germany | Automotive Products
Disaggregation of Revenue [Line Items]
Total revenue	91,793,541
Japan | Automotive Products
Disaggregation of Revenue [Line Items]
Total revenue	49,832,997
Other | Automotive Products
Disaggregation of Revenue [Line Items]
Total revenue	$ 173,025,849