Gentex (GNTX) 10-Q 5 May 17 2017 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2017	Apr. 21, 2017
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, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Amendment Flag	false
Trading Symbol	gntx
Entity Common Stock, Shares Outstanding		287,270,285

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2017	Dec. 31, 2016	[1]
CURRENT ASSETS
Cash and cash equivalents	$ 559,645,625	$ 546,477,075
Short-term investments	176,635,803	177,021,197
Accounts receivable, net	249,457,918	211,591,745
Inventories	197,088,251	189,311,437
Prepaid expenses and other	11,730,076	30,587,575
Total current assets	1,194,557,673	1,154,989,029
PLANT AND EQUIPMENT—NET	473,151,849	465,822,467
OTHER ASSETS
Goodwill	307,365,845	307,365,845
Long-term investments	61,512,162	49,894,363
Intangible Assets, net	303,450,000	308,275,000
Patents and other assets, net	23,255,137	23,273,129
Total other assets	695,583,144	688,808,337
Total assets	2,363,292,666	2,309,619,833
CURRENT LIABILITIES
Accounts payable	77,714,280	79,963,630
Accrued liabilities	196,641,584	69,894,349
Total current liabilities	274,355,864	149,857,979
LONG TERM DEBT	36,250,000	178,125,000
DEFERRED INCOME TAXES	77,915,264	71,212,620
TOTAL LIABILITIES	388,521,128	399,195,599
SHAREHOLDERS’ INVESTMENT
Common stock	17,266,545	17,264,251
Additional paid-in capital	701,980,783	683,446,463
Retained earnings	1,254,778,976	1,210,984,825
Accumulated other comprehensive income	745,234	(1,271,305)
Total shareholders’ investment	1,974,771,538	1,910,424,234
Total liabilities and shareholders’ investment	$ 2,363,292,666	$ 2,309,619,833
[1]	Note: The condensed consolidated balance sheet at December 31, 2016 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, 2017	Mar. 31, 2016
Income Statement [Abstract]
NET SALES	$ 453,535,250	$ 405,567,786
COST OF GOODS SOLD	277,734,465	246,876,998
Gross profit	175,800,785	158,690,788
OPERATING EXPENSES:
Engineering, research and development	25,152,257	23,091,209
Selling, general & administrative	16,221,408	14,750,589
Total operating expenses	41,373,665	37,841,798
Income from operations	134,427,120	120,848,990
OTHER INCOME (LOSS)
Investment income	1,472,527	790,041
Other Loss, net	(1,034,743)	(2,069,419)
Total Other Income (Loss)	437,784	(1,279,378)
Income before provision for income taxes	134,864,904	119,569,612
PROVISION FOR INCOME TAXES	37,308,163	39,289,618
NET INCOME	$ 97,556,741	$ 80,279,994
EARNINGS PER SHARE:
Basic (in dollars per share)	$ 0.34	$ 0.28
Diluted (in dollars per share)	0.33	0.28
Cash Dividends Declared per Share (in dollars per share)	$ 0.09	$ 0.085

Unaudited Condensed Consolidat4

Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 97,556,741	$ 80,279,994
Other comprehensive income (loss) before tax:
Foreign currency translation adjustments	188,590	324,844
Unrealized gains (losses) on derivatives	641,975	(1,351,557)
Unrealized gains (losses) on available-for sales securities, net	2,170,254	(319,349)
Other comprehensive income (loss), before tax	3,000,819	(1,346,062)
Expense (Benefit) for income taxes related to components of other comprehensive income (loss)	984,280	(584,816)
Other comprehensive income (loss), net of tax	2,016,539	(761,246)
Comprehensive Income	$ 99,573,280	$ 79,518,748

Unaudited Condensed Consolidat5

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2017		Mar. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 97,556,741		$ 80,279,994
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	25,181,854		22,839,030
Gain on disposal of assets	(146,261)		(10,900)
Loss on disposal of assets	359,959		577,916
Gain on sale of investments	(274,844)		(1,498,949)
Loss on sale of investments	21,431		1,961,673
Deferred income taxes	5,718,363		(2,403,818)
Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock	4,422,996		4,974,453
Change in operating assets and liabilities:
Accounts receivable, net	(37,866,173)		(28,020,070)
Inventories	(7,776,814)		(13,929,365)
Prepaid expenses and other	18,857,501		23,521,639
Accounts payable	(2,249,350)		13,065,406
Accrued liabilities, excluding dividends declared and short-term debt	27,385,768		50,511,519
Net cash provided by operating activities	131,191,171		151,868,528
Activity in available-for-sale securities:
Sales proceeds	1,316,280		43,417,073
Maturities and calls	6,100,000		0
Purchases	(16,225,018)		(25,154,245)
Plant and equipment additions	(27,119,993)		(20,329,035)
Proceeds from sale of plant and equipment	15,001		516,667
(Increase) Decrease in other assets	(588,361)		135,904
Net cash used for investing activities	(36,502,091)		(1,413,636)
CASH FLOWS USED FOR FINANCING ACTIVITIES:
Repayment of long-term debt	(41,875,000)		(16,875,000)
Issuance of common stock from stock plan transactions	17,237,232		10,678,450
Cash dividends paid	(25,896,377)		(24,759,481)
Repurchases of common stock	(30,986,385)		(44,585,668)
Net cash used for financing activities	(81,520,530)		(75,541,699)
NET INCREASE IN CASH AND CASH EQUIVALENTS	13,168,550		74,913,193
CASH AND CASH EQUIVALENTS, beginning of period	546,477,075	[1]	551,557,527
CASH AND CASH EQUIVALENTS, end of period	$ 559,645,625		$ 626,470,720
[1]	Note: The condensed consolidated balance sheet at December 31, 2016 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, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements included herein have been prepared by the Company, pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted pursuant to such rules and regulations, although the Company believes that the disclosures are adequate to make the information presented not misleading. It is suggested that these unaudited condensed consolidated financial statements be read in conjunction with the financial statements and notes thereto included in the Company's 2016 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, 2017 , and the results of operations and cash flows for the interim periods presented.

Adoption of New Accounting Stan

Adoption of New Accounting Standards	3 Months Ended
	Mar. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Adoption of New Accounting Standards	Adoption of New Accounting Standards In May 2014 the Financial Accounting Standards Board (FASB) issued the Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606) , that will supersede nearly all existing revenue recognition guidance under US GAAP. The core principle of the guidance is that an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The standard was originally to be effective for public entities for annual and interim periods beginning after December 15, 2016. On July 9, 2015 the FASB decided to defer by one year the effective dates of the new standard for both public and nonpublic entities reporting under US GAAP. Early adoption would be permitted for all entities, but not before the original public entity effective date (i.e. annual and interim periods beginning after December 16, 2016). Entities can choose to apply the standard using either the full retrospective approach or a modified retrospective approach. Entities electing the full retrospective adoption will apply the standard to each period presented in the financial statements. This means that entities will have to apply the new guidance as if it had been in effect since the inception of all its contracts with customers presented in the financial statements. Entities that elect the modified retrospective approach will apply the guidance retrospectively only to the most current period presented in the financial statements. This means that entities will have to recognize the cumulative effect of initially applying the new standard as an adjustment to the opening balance of retained earnings at the date of initial application. The new revenue standard will be applied to contracts that are in progress at the date of initial application. The Company will adopt ASU 2014-09 in the first quarter of 2018 and apply the modified retrospective approach. The Company has continued to monitor FASB activity related to the new standard and is currently assessing existing contracts with customers as a part of determining the potential effect the new standard will have on its consolidated financial statements. The Company currently anticipates that the adoption of ASU No. 2014-09 could impact the accounting treatment of certain contracts, as well as pre-production engineering, development and tooling costs related to products manufactured for our customers under long-term supply agreements. 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. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , which amends Accounting Standards Codification ("ASC") Topic 718, Compensation - Stock Compensation. ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. Under previous guidance, excess tax benefits and deficiencies from stock-based compensation arrangements were recorded in equity when the awards vested or were settled. ASU 2016-09 requires prospective recognition of excess tax benefits and deficiencies in the income statement as a component of the income tax provision. In addition, under ASU 2016-09, excess income tax benefits from stock-based compensation arrangements are classified as cash flow from operations, rather than as cash flow from financing activities. ASU 2016-09 also allows for the Company to make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest or account for forfeitures when they occur. The Company will continue to apply its existing entity-wide policy to estimate the number of awards expected to be forfeited. Impact to Consolidated Statements of Income One of the more significant impacts of adopting ASU 2016-09 is the required change in how the Company recognizes the excess tax benefits or deficiencies related to share-based compensation. For example, prior to adopting ASU 2016-09 such benefits and deficiencies were credited or charged, respectively, to additional paid-in capital in the Company’s Consolidated Balance Sheets. Under ASU 2016-09, these benefits and deficiencies are recognized as a discrete tax benefit or discrete tax expense, in the Company’s Consolidated Statements of Income. For the three months ended March 31, 2017, the Company recognized a discrete tax benefit of $1.8 million related to net tax benefits from share-based compensation. ASU 2016-09 requires companies to adopt the amendment related to accounting for benefits and deficiencies on a prospective basis only. As a result, no change has been made to the Consolidated Statements of Income for the three months ended March 31, 2016 related to the $0.4 million of net tax expense the Company recognized as additional paid-in capital during such three months. Net tax expense of $0.4 million recognized as additional paid-in-capital during the three months ended March 31, 2016 includes gross tax benefits of $0.1 million net of $0.5 million tax expense. In consideration of the impact of the adoption of this standard to earnings per share, the total impact of adoption of this standard to the earnings per share calculation was less than $.01 for the three month periods ending March 31, 2017. Impact to Consolidated Statements of Cash Flows In addition to the income tax consequences described above, under ASU 2016-09 all tax benefits related to share-based payments are reported as cash flows from operating activities along with all other income tax cash flows. Previously, tax benefits from share-based payment arrangements were reported as cash flows from financing activities. With respect to the classification of tax benefits on the statement of cash flows, ASU 2016-09 allows companies to elect either a prospective or retrospective application. The Company has elected to apply this classification amendment retrospectively. As a result, the Company elected to reclassify $0.4 million of tax expense previously reported as cash flows from financing activities on the Company’s Consolidated Statement of Cash Flows for the three months ended March 31, 2016 as cash flows from operating activities. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows , which updates the guidance as to how certain cash receipts and cash payments should be presented and classified within the statement of cash flows. The update is intended to reduce the existing diversity in practice. The amended guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017, with early adoption permitted, including adoption in an interim period. The Company is in the process of assessing the potential effect the new standard will have on its consolidated financial statements.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 2017
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, 2016 and March 31, 2017 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, 2017 : Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 33,620,379 $ (17,147,912 ) $ 16,472,467 various Other Intangible Assets HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (52,500,000 ) 127,500,000 12 years Existing Customer Platforms 43,000,000 (15,050,000 ) 27,950,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total Other Intangible Assets $ 371,000,000 $ (67,550,000 ) $ 303,450,000 Total Patents & Other Intangible Assets $ 404,620,379 $ (84,697,912 ) $ 319,922,467 As of December 31, 2016 : Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 33,002,468 $ (16,481,728 ) $ 16,520,740 various HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (48,750,000 ) $ 131,250,000 12 years Existing Customer Platforms 43,000,000 (13,975,000 ) $ 29,025,000 10 years Exclusive Licensing Agreement 96,000,000 — $ 96,000,000 Indefinite Total other identifiable intangible assets $ 371,000,000 $ (62,725,000 ) $ 308,275,000 Total Patents & Other Intangible Assets $ 404,002,468 $ (79,206,728 ) $ 324,795,740 Amortization expense on patents and intangible assets was approximately $5.6 million during the three month period ended March 31, 2017 , compared to approximately $5.6 million for the same period ended March 31, 2016 . Excluding the impact of any future acquisitions, the Company continues to estimate amortization expense for each of the years ended December 31, 2017, 2018, 2019, 2020 and 2021 to be approximately $22 million annually.

Investments

Investments	3 Months Ended
	Mar. 31, 2017
Investments [Abstract]
Investments	Investments The Company follows the provisions of ASC 820, “Fair Value Measurements and Disclosures” for its financial assets and liabilities, and for its non-financial assets and liabilities subject to fair value measurements. ASC 820 provides a framework for measuring the fair value of assets and liabilities. This framework is intended to provide increased consistency in how fair value determinations are made under various existing accounting standards that permit, or in some cases, require estimates of fair-market value. This standard also expanded financial statement disclosure requirements about a company’s use of fair-value measurements, including the effect of such measure on earnings. The cost of securities sold is based on the specific identification method. The Company’s common stocks and certain mutual funds are classified as available for sale and are stated at fair value based on quoted market prices, and as such are classified as Level 1 assets. The Company determines the fair value of its government securities, corporate bonds, and certain mutual funds 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 classified as available for sale, and are considered as Level 1 assets. These investments are carried at cost, which approximates fair value. Assets or liabilities that have recurring fair value measurements are shown below as of March 31, 2017 , and December 31, 2016 : As of March 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 March 31, 2017 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 559,645,625 $ 559,645,625 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Government Securities 16,996,070 — 16,996,070 — Mutual Funds 26,322,271 — 26,322,271 — Corporate Bonds 3,054,720 — 3,054,720 — Other 262,742 262,742 — — Long-Term Investments: Corporate Bonds 10,829,545 — 10,829,545 — Government Securities 6,050,190 — 6,050,190 — Common Stocks 13,305,263 13,305,263 — — Mutual Funds – Equity 30,583,753 30,583,753 — — Preferred Stock 743,411 743,411 — $ — Total $ 797,793,590 $ 734,540,794 $ 63,252,796 $ — As of December 31, 2016 : 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, 2015 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 546,477,075 $ 546,477,075 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Government Securities 13,993,480 — 13,993,480 — Mutual Funds 26,116,681 26,116,681 — Corporate Bonds 6,698,382 — 6,698,382 — Other 212,653 212,653 — — Long-Term Investments: Corporate Bonds 1,948,556 1,948,556 — Common Stocks 12,849,007 12,849,007 — — Mutual Funds 28,872,010 28,872,010 — — Preferred Stock 714,000 714,000 — Government Securities 5,510,790 5,510,790 — Total $ 773,392,634 $ 719,124,745 $ 54,267,889 $ — The amortized cost, unrealized gains and losses, and market value of investment securities are shown as of March 31, 2017 , and December 31, 2016 : As of March 31, 2017 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities $ 17,017,432 $ — $ (21,362 ) $ 16,996,070 Mutual Funds 26,458,425 41,908 (178,062 ) 26,322,271 Corporate Bonds 3,058,352 — (3,632 ) 3,054,720 Other 262,742 — — 262,742 Long-Term Investments: Corporate Bonds 10,823,853 9,342 (3,650 ) 10,829,545 Government Securities 6,059,283 — (9,093 ) 6,050,190 Common Stocks 9,879,067 3,613,008 (186,812 ) 13,305,263 Mutual Funds – Equity 27,382,364 3,206,612 (5,223 ) 30,583,753 Preferred Stock 745,462 9,536 (11,587 ) 743,411 Total $ 231,686,980 $ 6,880,406 $ (419,421 ) $ 238,147,965 As of December 31, 2016 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities $ 14,003,644 $ — $ (10,164 ) $ 13,993,480 Mutual Funds 26,326,674 27,459 (237,452 ) 26,116,681 Corporate Bonds 6,706,721 — (8,339 ) 6,698,382 Other 212,653 — — 212,653 Long-Term Investments: Corporate Bonds 1,955,292 — (6,736 ) 1,948,556 Common Stocks 9,825,550 3,349,962 (326,505 ) 12,849,007 Mutual Funds 27,329,164 1,830,992 (288,146 ) 28,872,010 Preferred Stock 745,462 360 (31,822 ) 714,000 Government Securities 5,519,668 661 (9,539 ) 5,510,790 Total $ 222,624,828 $ 5,209,434 $ (918,703 ) $ 226,915,559 Unrealized losses on investments as of March 31, 2017 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 321,258 $ 51,576,425 Greater than one year 98,163 269,524 Total $ 419,421 $ 51,845,949 Unrealized losses on investments as of December 31, 2016 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 767,612 $ 55,574,292 Greater than one year 151,091 358,120 Total $ 918,703 $ 55,932,412 ASC 320, “Accounting for Certain Investments in Debt and Equity Securities”, as amended, provides guidance on determining when an investment is other than temporarily impaired. The Company reviews its equity investment portfolio for any unrealized losses that would be deemed other-than-temporary and require the recognition of an impairment loss in income. If the cost of an investment exceeds its fair value, the Company evaluates, among other factors, general market conditions, the duration and extent to which the fair value is less than cost, and the Company’s intent and ability to hold the investments. Management also considers the type of security, related-industry and sector performance, as well as published investment ratings and analyst reports, to evaluate its portfolio. Once a decline in fair value is determined to be other than temporary, an impairment charge is recorded and a new cost basis in the investment is established. If market, industry, and/or investee conditions deteriorate, the Company may incur future impairments. No equity investment losses were considered to be other than temporary during the periods presented. The Company additionally 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, 2017 , have contractual maturities as follows: Due within one year $ 150,050,790 Due between one and five years 17,623,180 Due over five years — $ 167,673,970

Inventories

Inventories	3 Months Ended
	Mar. 31, 2017
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consisted of the following at the respective balance sheet dates: March 31, 2017 December 31, 2016 Raw materials $ 122,534,856 $ 115,099,569 Work-in-process 33,896,522 32,509,368 Finished goods 40,656,873 41,702,500 Total Inventory $ 197,088,251 $ 189,311,437

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2017
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, 2017 2016 Numerators: Numerator for both basic and diluted EPS, net income $ 97,556,741 $ 80,279,994 Denominators: Denominator for basic EPS, weighted-average shares outstanding 287,408,900 289,210,621 Potentially dilutive shares resulting from stock plans 4,070,938 2,105,732 Denominator for diluted EPS 291,479,838 291,316,353 Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive 2,311 7,866,330

Stock-Based Compensation Plans

Stock-Based Compensation Plans	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans As of March 31, 2017 , 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, 2016 , for additional information related to these stock-based compensation plans. The Company recognized compensation expense for share-based payments of $3,484,240 for the three months ended March 31, 2017 , and $4,022,382 for the three months ended March 31, 2016 . Compensation cost capitalized as part of inventory as of March 31, 2017 and 2016 was $226,119 and $292,187 , 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, 2017 2016 Dividend Yield (1) 2.18 % 2.15 % Expected volatility (2) 29.81 % 34.53 % Risk-free interest rate (3) 2.10 % 1.38 % Expected term of options (years) (4) 4.09 4.18 Weighted-avg. grant date fair value $4.51 $3.67 (1) Represents the Company’s estimated cash dividend yield over the expected term of option grant. (2) Amount is determined based on analysis of historical price volatility of the Company’s common stock. The expected volatility is based on the daily percentage change in the price of the stock over a period equal to the expected term of the option grant. (3) Represents the U.S. Treasury yield over the expected term of the option grant. (4) Represents the period of time that options granted are expected to be outstanding. Based on analysis of historical option exercise activity, the Company has determined that all employee groups exhibit similar exercise and post-vesting termination behavior. Under the employee stock option plan, the option exercise price equals the stock’s market price on date of grant. The options vest after one to five years, and expire after five to seven years. As of March 31, 2017 , there was $15,329,604 of unrecognized compensation cost related to share-based payments which is expected to be recognized over the vesting periods. Non-employee Director Stock Option Plan The Company has a non-employee director stock option plan covering 1,000,000 shares of common stock. As of March 31, 2017 , there was no unrecognized compensation cost under the non-employee director plan related to share-based payments. The Company has granted options on 371,000 shares under the non-employee director plan through March 31, 2017 . 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, 2017 , the Company has granted 659,810 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 long-term performance and to increase their ownership in the Company. Shares awarded under the restricted stock plan entitle the shareholder to all rights of common stock ownership except that the shares may not be sold, transferred, pledged, exchanged or otherwise disposed of during the restriction period. The restriction period is determined by the Compensation Committee, appointed by the Board of Directors, but may not exceed ten years under the terms of the plan. As of March 31, 2017 , the Company had unearned stock-based compensation of $14,924,917 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, 2017 was $940,811 .

Comprehensive Income

Comprehensive Income	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Comprehensive Income	Comprehensive Income Comprehensive income reflects the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. For the Company, comprehensive income represents net income adjusted for unrealized gains and losses on certain investments, 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, 2017 2016 Foreign currency translation adjustments: Balance at beginning of period $ (2,862,999 ) $ (44,909 ) Other Comprehensive income before reclassifications 188,590 324,844 Net current-period change 188,590 324,844 Balance at end of period (2,674,409 ) 279,935 Unrealized gains (losses) on available-for-sale securities: Balance at beginning of period 2,788,975 829,907 Other Comprehensive income (loss) before reclassifications 1,575,383 (508,348 ) Amounts reclassified from accumulated other comprehensive income (164,718 ) 300,771 Net current-period change 1,410,665 (207,577 ) Balance at end of period 4,199,640 622,330 Unrealized gains (losses) on derivatives: Balance at beginning of period (1,197,281 ) (1,915,834 ) Other comprehensive income (loss) before reclassifications 147,318 (1,237,475 ) Amounts reclassified from accumulated other comprehensive income 269,966 358,962 Net current-period change 417,284 (878,513 ) Balance at end of period (779,997 ) (2,794,347 ) Accumulated other comprehensive income (loss), end of period $ 745,234 $ (1,892,082 ) The following table presents details of reclassifications out of other comprehensive income for the three months ended March 31, 2017 and 2016 . 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, 2016 2015 Unrealized gains on available-for-sale securities Realized gain (loss) on sale of securities $ 253,413 $ (462,724 ) Other, net Provision for Income Taxes (88,695 ) 161,953 Provision for Income Taxes $ 164,718 $ (300,771 ) Net of tax Unrealized gains (losses) on derivatives Realized loss on interest rate swap $ (415,333 ) $ (552,250 ) Other, net Provision for Income Taxes 145,367 193,288 Provision for Income Taxes $ (269,966 ) $ (358,962 ) Net of tax Total reclassifications for the period $ (105,248 ) $ (659,733 ) Net of tax

Debt and Financing Arrangements

Debt and Financing Arrangements	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Debt and Financing Arrangements	Debt and Financing Arrangements Credit Agreement 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 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, 2017 , the Company made principal repayments of $41.9 million , plus accrued interest, on the Term Loan and Revolver. The aforementioned payments include a payment made by the Company of $40.0 million on the Revolver during the first quarter of 2017, which was in addition to scheduled amounts due. The Company used cash and cash equivalents to fund the payments. The Company additionally reclassified $100 million of long-term debt to short-term debt as a result of the Company's current plans to make accelerated debt payments over the course of the next year. As of March 31, 2017 , $20.8 million was outstanding on the Revolver with availability of an additional $129.2 million . Under current terms of the Term Loan, the Company is required to make principal repayments of $7.5 million annually, but currently intends to make accelerated debt repayments through the maturity date of the Term Loan. As of March 31, 2017 , $123.8 million was outstanding under the Term Loan. As of March 31, 2017 , 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, 2017 , the interest rate on its borrowings is equal to 1.99% . 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 $0.9 million during the three months ended March 31, 2017 , and $0.9 million during the three months ended March 31, 2016 . The Credit Agreement contains customary representations and warranties and certain covenants that place certain limitations on the Company. As of March 31, 2017 , the Company was in compliance with its covenants under the Credit Agreement. Interest Rate Swap On October 1, 2014 the Company entered into an interest rate swap transaction with a bank (“Counterparty”). The Counterparty is among the syndicate of lenders under the existing Credit Agreement entered into on September 27, 2013. The Company entered into the interest rate swap transaction to mitigate the Company’s floating rate interest risk on an aggregate of $150 million of the Company’s debt that is currently outstanding under the Credit Agreement. The interest rate swap has an effective date of July 31, 2015 and a termination date of September 27, 2018 (which is the expiration date of the Credit Agreement). The Company is required to make certain monthly fixed rate payments to the Counterparty calculated on a notional amount of $150 million for the rate swap, while the Counterparty is obligated to make monthly floating rate payments to the Company referencing the same notional amount. The interest rate swap transaction has the effect of fixing the annual interest rate payable on $150 million of the Company’s outstanding debt under its existing credit facility to 1.89% , as of the effective date. The notional amounts of the interest rate swap agreement are used to measure interest to be paid or received and do not represent the amount of exposure to credit loss. This derivative instrument has been designated as a cash flow hedge of the variable interest payments on the related debt. Interest expense are netted within the "Other, net" section of the Condensed Consolidated Statements of Income , and interest expense associated with the interest rate swap was $0.4 million during the three months ended March 31, 2017 , and $0.6 million during the three months ended March 31, 2016 . Notwithstanding the terms of the interest rate swap transaction, the Company is ultimately obligated for all amounts due and payable under its existing Credit Agreement. The notional amount of the Company's derivative instruments are as follows: March 31, 2017 December 31, 2016 Interest Rate Swap $ 150,000,000 $ 150,000,000 The following table sets forth financial assets and liabilities measured at fair value related to the interest rate swap agreement and the respective pricing levels to which the fair value measurements are classified within the fair value hierarchy. The Company uses the market approach to derive the value of its level 2 fair value measurements. Interest rate swaps are valued using publicized swap curves. Fair Value Measurements Quoted Prices with Other Observable Inputs (Level 2) March 31, 2017 December 31, 2016 Financial assets: Interest Rate Swap Asset $ — $ — Financial Liabilities: Interest Rate Swap Liability (Other Accrued Liabilities) $ 1,199,995 $ 1,841,970 Based on loan balances as of March 31, 2017 and the effective interest swap date of July 31, 2015, a one percent increase in the Company's borrowing rate would increase net interest expense paid by the Company on its borrowings by less than $0.1 million dollars on an annual basis.

Equity

Equity	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Equity	Equity The increase in common stock during the three months ended March 31, 2017 , was primarily due to the issuance of 1,511,640 shares of the Company’s common stock under the Company’s stock-based compensation plans, which was partially offset by share repurchases of 1,473,403 shares pursuant to the Company's previously announced share repurchase plan, for a net increase of 38,237 shares. The Company announced a $.005 per share increase in its quarterly cash dividend rate during the second quarter of 2016. As such, the Company recorded a cash dividend of $0.090 during the first quarter of 2017 as compared to a cash dividend of $.085 per share during the first quarter of 2016. The first quarter 2017 dividend of $25.9 million , was declared on March 6, 2017 , and was paid on April 19, 2017 .

Contingencies

Contingencies	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies The Company is periodically involved in legal proceedings, legal actions and claims arising in the normal course of business, including proceedings relating to product liability, intellectual property, safety and health, employment and other matters. Such matters are subject to many uncertainties and outcomes are not predictable. The Company does not believe, however, that at the current time any of these matters constitute material pending legal proceedings that will have a material adverse effect on the financial position or future results of operations of the Company.

Segment Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 2017
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, 2017 2016 Revenue: Automotive Products $ 445,652,575 $ 393,968,947 Other 7,882,675 11,598,839 Total $ 453,535,250 $ 405,567,786 Income from operations: Automotive Products $ 132,504,957 $ 115,980,617 Other 1,922,163 4,868,373 Total $ 134,427,120 $ 120,848,990

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate was 27.7% in the three months ended March 31, 2017 compared to 32.9% for the same period in 2016. Effective tax rates for these quarters differ from statutory federal income tax rates, due to the domestic manufacturing deduction, provisions for state and local income taxes and permanent tax differences. The decrease in the effective tax rate for the three months ended March 31, 2017 compared to the same period of 2016 is primarily due to favorable discrete items that impacted the Company's tax provision in the amount of $5.6 million , of which $3.8 million was related to a change in tax method and $1.8 million was related to the adoption of ASU 2016-09 during the most recently completed quarter, which requires prospective recognition of excess tax benefits and deficiencies from stock-based compensation arrangements in the income statement as a component of the income tax provision. The new ASU and its impacts on the Company's Consolidated Statements of Income and Statements of Cash Flows are further described in Note 2 of the Notes to the Consolidated Financial Statements in this Form 10-Q.

Adoption of New Accounting St19

Adoption of New Accounting Standards (Policies)	3 Months Ended
	Mar. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Adoption of new Accounting Standards	Adoption of New Accounting Standards In May 2014 the Financial Accounting Standards Board (FASB) issued the Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606) , that will supersede nearly all existing revenue recognition guidance under US GAAP. The core principle of the guidance is that an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The standard was originally to be effective for public entities for annual and interim periods beginning after December 15, 2016. On July 9, 2015 the FASB decided to defer by one year the effective dates of the new standard for both public and nonpublic entities reporting under US GAAP. Early adoption would be permitted for all entities, but not before the original public entity effective date (i.e. annual and interim periods beginning after December 16, 2016). Entities can choose to apply the standard using either the full retrospective approach or a modified retrospective approach. Entities electing the full retrospective adoption will apply the standard to each period presented in the financial statements. This means that entities will have to apply the new guidance as if it had been in effect since the inception of all its contracts with customers presented in the financial statements. Entities that elect the modified retrospective approach will apply the guidance retrospectively only to the most current period presented in the financial statements. This means that entities will have to recognize the cumulative effect of initially applying the new standard as an adjustment to the opening balance of retained earnings at the date of initial application. The new revenue standard will be applied to contracts that are in progress at the date of initial application. The Company will adopt ASU 2014-09 in the first quarter of 2018 and apply the modified retrospective approach. The Company has continued to monitor FASB activity related to the new standard and is currently assessing existing contracts with customers as a part of determining the potential effect the new standard will have on its consolidated financial statements. The Company currently anticipates that the adoption of ASU No. 2014-09 could impact the accounting treatment of certain contracts, as well as pre-production engineering, development and tooling costs related to products manufactured for our customers under long-term supply agreements. 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. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , which amends Accounting Standards Codification ("ASC") Topic 718, Compensation - Stock Compensation. ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. Under previous guidance, excess tax benefits and deficiencies from stock-based compensation arrangements were recorded in equity when the awards vested or were settled. ASU 2016-09 requires prospective recognition of excess tax benefits and deficiencies in the income statement as a component of the income tax provision. In addition, under ASU 2016-09, excess income tax benefits from stock-based compensation arrangements are classified as cash flow from operations, rather than as cash flow from financing activities. ASU 2016-09 also allows for the Company to make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest or account for forfeitures when they occur. The Company will continue to apply its existing entity-wide policy to estimate the number of awards expected to be forfeited. Impact to Consolidated Statements of Income One of the more significant impacts of adopting ASU 2016-09 is the required change in how the Company recognizes the excess tax benefits or deficiencies related to share-based compensation. For example, prior to adopting ASU 2016-09 such benefits and deficiencies were credited or charged, respectively, to additional paid-in capital in the Company’s Consolidated Balance Sheets. Under ASU 2016-09, these benefits and deficiencies are recognized as a discrete tax benefit or discrete tax expense, in the Company’s Consolidated Statements of Income. For the three months ended March 31, 2017, the Company recognized a discrete tax benefit of $1.8 million related to net tax benefits from share-based compensation. ASU 2016-09 requires companies to adopt the amendment related to accounting for benefits and deficiencies on a prospective basis only. As a result, no change has been made to the Consolidated Statements of Income for the three months ended March 31, 2016 related to the $0.4 million of net tax expense the Company recognized as additional paid-in capital during such three months. Net tax expense of $0.4 million recognized as additional paid-in-capital during the three months ended March 31, 2016 includes gross tax benefits of $0.1 million net of $0.5 million tax expense. In consideration of the impact of the adoption of this standard to earnings per share, the total impact of adoption of this standard to the earnings per share calculation was less than $.01 for the three month periods ending March 31, 2017. Impact to Consolidated Statements of Cash Flows In addition to the income tax consequences described above, under ASU 2016-09 all tax benefits related to share-based payments are reported as cash flows from operating activities along with all other income tax cash flows. Previously, tax benefits from share-based payment arrangements were reported as cash flows from financing activities. With respect to the classification of tax benefits on the statement of cash flows, ASU 2016-09 allows companies to elect either a prospective or retrospective application. The Company has elected to apply this classification amendment retrospectively. As a result, the Company elected to reclassify $0.4 million of tax expense previously reported as cash flows from financing activities on the Company’s Consolidated Statement of Cash Flows for the three months ended March 31, 2016 as cash flows from operating activities. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows , which updates the guidance as to how certain cash receipts and cash payments should be presented and classified within the statement of cash flows. The update is intended to reduce the existing diversity in practice. The amended guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017, with early adoption permitted, including adoption in an interim period. The Company is in the process of assessing the potential effect the new standard will have on its consolidated financial statements.

Goodwill and Other Intangible20

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2017
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, 2017 : Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 33,620,379 $ (17,147,912 ) $ 16,472,467 various Other Intangible Assets HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (52,500,000 ) 127,500,000 12 years Existing Customer Platforms 43,000,000 (15,050,000 ) 27,950,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total Other Intangible Assets $ 371,000,000 $ (67,550,000 ) $ 303,450,000 Total Patents & Other Intangible Assets $ 404,620,379 $ (84,697,912 ) $ 319,922,467 As of December 31, 2016 : Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 33,002,468 $ (16,481,728 ) $ 16,520,740 various HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (48,750,000 ) $ 131,250,000 12 years Existing Customer Platforms 43,000,000 (13,975,000 ) $ 29,025,000 10 years Exclusive Licensing Agreement 96,000,000 — $ 96,000,000 Indefinite Total other identifiable intangible assets $ 371,000,000 $ (62,725,000 ) $ 308,275,000 Total Patents & Other Intangible Assets $ 404,002,468 $ (79,206,728 ) $ 324,795,740

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2017
Investments [Abstract]
Investment Securities Stated at Fair Value	Assets or liabilities that have recurring fair value measurements are shown below as of March 31, 2017 , and December 31, 2016 : As of March 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 March 31, 2017 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 559,645,625 $ 559,645,625 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Government Securities 16,996,070 — 16,996,070 — Mutual Funds 26,322,271 — 26,322,271 — Corporate Bonds 3,054,720 — 3,054,720 — Other 262,742 262,742 — — Long-Term Investments: Corporate Bonds 10,829,545 — 10,829,545 — Government Securities 6,050,190 — 6,050,190 — Common Stocks 13,305,263 13,305,263 — — Mutual Funds – Equity 30,583,753 30,583,753 — — Preferred Stock 743,411 743,411 — $ — Total $ 797,793,590 $ 734,540,794 $ 63,252,796 $ — As of December 31, 2016 : 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, 2015 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 546,477,075 $ 546,477,075 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Government Securities 13,993,480 — 13,993,480 — Mutual Funds 26,116,681 26,116,681 — Corporate Bonds 6,698,382 — 6,698,382 — Other 212,653 212,653 — — Long-Term Investments: Corporate Bonds 1,948,556 1,948,556 — Common Stocks 12,849,007 12,849,007 — — Mutual Funds 28,872,010 28,872,010 — — Preferred Stock 714,000 714,000 — Government Securities 5,510,790 5,510,790 — Total $ 773,392,634 $ 719,124,745 $ 54,267,889 $ —
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 March 31, 2017 , and December 31, 2016 : As of March 31, 2017 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities $ 17,017,432 $ — $ (21,362 ) $ 16,996,070 Mutual Funds 26,458,425 41,908 (178,062 ) 26,322,271 Corporate Bonds 3,058,352 — (3,632 ) 3,054,720 Other 262,742 — — 262,742 Long-Term Investments: Corporate Bonds 10,823,853 9,342 (3,650 ) 10,829,545 Government Securities 6,059,283 — (9,093 ) 6,050,190 Common Stocks 9,879,067 3,613,008 (186,812 ) 13,305,263 Mutual Funds – Equity 27,382,364 3,206,612 (5,223 ) 30,583,753 Preferred Stock 745,462 9,536 (11,587 ) 743,411 Total $ 231,686,980 $ 6,880,406 $ (419,421 ) $ 238,147,965 As of December 31, 2016 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities $ 14,003,644 $ — $ (10,164 ) $ 13,993,480 Mutual Funds 26,326,674 27,459 (237,452 ) 26,116,681 Corporate Bonds 6,706,721 — (8,339 ) 6,698,382 Other 212,653 — — 212,653 Long-Term Investments: Corporate Bonds 1,955,292 — (6,736 ) 1,948,556 Common Stocks 9,825,550 3,349,962 (326,505 ) 12,849,007 Mutual Funds 27,329,164 1,830,992 (288,146 ) 28,872,010 Preferred Stock 745,462 360 (31,822 ) 714,000 Government Securities 5,519,668 661 (9,539 ) 5,510,790 Total $ 222,624,828 $ 5,209,434 $ (918,703 ) $ 226,915,559
Schedule of Unrealized Loss on Investments	Unrealized losses on investments as of March 31, 2017 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 321,258 $ 51,576,425 Greater than one year 98,163 269,524 Total $ 419,421 $ 51,845,949 Unrealized losses on investments as of December 31, 2016 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 767,612 $ 55,574,292 Greater than one year 151,091 358,120 Total $ 918,703 $ 55,932,412
Investments Classified by Contractual Maturity Date	Fixed income securities as of March 31, 2017 , have contractual maturities as follows: Due within one year $ 150,050,790 Due between one and five years 17,623,180 Due over five years — $ 167,673,970

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2017
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories consisted of the following at the respective balance sheet dates: March 31, 2017 December 31, 2016 Raw materials $ 122,534,856 $ 115,099,569 Work-in-process 33,896,522 32,509,368 Finished goods 40,656,873 41,702,500 Total Inventory $ 197,088,251 $ 189,311,437

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2017
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, 2017 2016 Numerators: Numerator for both basic and diluted EPS, net income $ 97,556,741 $ 80,279,994 Denominators: Denominator for basic EPS, weighted-average shares outstanding 287,408,900 289,210,621 Potentially dilutive shares resulting from stock plans 4,070,938 2,105,732 Denominator for diluted EPS 291,479,838 291,316,353 Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive 2,311 7,866,330

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2017
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, 2017 2016 Dividend Yield (1) 2.18 % 2.15 % Expected volatility (2) 29.81 % 34.53 % Risk-free interest rate (3) 2.10 % 1.38 % Expected term of options (years) (4) 4.09 4.18 Weighted-avg. grant date fair value $4.51 $3.67 (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)	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Schedule of net changes in the Company's accumulated other comprehensive income by component	The following table presents the net changes in the Company's accumulated other comprehensive income (loss) by component: (All amounts shown are net of tax). Three Months Ended March 31, 2017 2016 Foreign currency translation adjustments: Balance at beginning of period $ (2,862,999 ) $ (44,909 ) Other Comprehensive income before reclassifications 188,590 324,844 Net current-period change 188,590 324,844 Balance at end of period (2,674,409 ) 279,935 Unrealized gains (losses) on available-for-sale securities: Balance at beginning of period 2,788,975 829,907 Other Comprehensive income (loss) before reclassifications 1,575,383 (508,348 ) Amounts reclassified from accumulated other comprehensive income (164,718 ) 300,771 Net current-period change 1,410,665 (207,577 ) Balance at end of period 4,199,640 622,330 Unrealized gains (losses) on derivatives: Balance at beginning of period (1,197,281 ) (1,915,834 ) Other comprehensive income (loss) before reclassifications 147,318 (1,237,475 ) Amounts reclassified from accumulated other comprehensive income 269,966 358,962 Net current-period change 417,284 (878,513 ) Balance at end of period (779,997 ) (2,794,347 ) Accumulated other comprehensive income (loss), end of period $ 745,234 $ (1,892,082 )
Schedule of reclassifications out of other comprehensive income	The following table presents details of reclassifications out of other comprehensive income for the three months ended March 31, 2017 and 2016 . 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, 2016 2015 Unrealized gains on available-for-sale securities Realized gain (loss) on sale of securities $ 253,413 $ (462,724 ) Other, net Provision for Income Taxes (88,695 ) 161,953 Provision for Income Taxes $ 164,718 $ (300,771 ) Net of tax Unrealized gains (losses) on derivatives Realized loss on interest rate swap $ (415,333 ) $ (552,250 ) Other, net Provision for Income Taxes 145,367 193,288 Provision for Income Taxes $ (269,966 ) $ (358,962 ) Net of tax Total reclassifications for the period $ (105,248 ) $ (659,733 ) Net of tax

Debt and Financing Arrangemen26

Debt and Financing Arrangements (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Schedule of notional amount of the Company's derivative instruments	The notional amount of the Company's derivative instruments are as follows: March 31, 2017 December 31, 2016 Interest Rate Swap $ 150,000,000 $ 150,000,000
Schedule of financial assets and liabilities measured at fair value in the consolidated balance sheets	The Company uses the market approach to derive the value of its level 2 fair value measurements. Interest rate swaps are valued using publicized swap curves. Fair Value Measurements Quoted Prices with Other Observable Inputs (Level 2) March 31, 2017 December 31, 2016 Financial assets: Interest Rate Swap Asset $ — $ — Financial Liabilities: Interest Rate Swap Liability (Other Accrued Liabilities) $ 1,199,995 $ 1,841,970

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2017
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, 2017 2016 Revenue: Automotive Products $ 445,652,575 $ 393,968,947 Other 7,882,675 11,598,839 Total $ 453,535,250 $ 405,567,786 Income from operations: Automotive Products $ 132,504,957 $ 115,980,617 Other 1,922,163 4,868,373 Total $ 134,427,120 $ 120,848,990

Adoption of New Accounting St28

Adoption of New Accounting Standards (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Recognized a discrete tax benefit	$ 1,800,000	$ 1,800,000
Reclassified tax benefits to operating activities	81,520,530	75,541,699
Cash flows from operating activities	$ 131,191,171	151,868,528
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassified tax benefits to operating activities		400,000
Cash flows from operating activities		400,000
Accounting Standards Update 2016-09 [Member] | Additional Paid-in Capital [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax benefit recognized as additional paid-in capital		(400,000)
Tax benefit recognized as additional paid-in capital, gross		100,000
Tax benefit recognized as additional paid-in capital, tax		$ 500,000

Goodwill and Other Intangible29

Goodwill and Other Intangible Assets (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016		Sep. 27, 2013
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Goodwill	$ 307,365,845		$ 307,365,845	[1]
Amortization expense, 2017	22,000,000
Amortization expense, 2018	22,000,000
Amortization expense, 2019	22,000,000
Amortization expense, 2020	22,000,000
Amortization expense, 2021	22,000,000
HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Goodwill					$ 307,400,000
Accumulated amortization	67,550,000		62,725,000
Gentex Patents
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Accumulated amortization	17,147,912		16,481,728
Patents and Other Intangible Assets
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Accumulated amortization	84,697,912		$ 79,206,728
Patents and Other Intangible Assets | HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Amortization expense	$ 5,600,000	$ 5,600,000
[1]	Note: The condensed consolidated balance sheet at December 31, 2016 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 Intangible30

Goodwill and Other Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 303,450,000	$ 308,275,000	[1]
Gentex Patents
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	33,620,379	33,002,468
Finite-lived intangible assets, accumulated amortization	(17,147,912)	(16,481,728)
Finite-lived intangible assets, net	16,472,467	16,520,740
Patents and Other Intangible Assets
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	(84,697,912)	(79,206,728)
Intangible assets, gross	404,620,379	404,002,468
Intangible assets, net	319,922,467	324,795,740
HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	(67,550,000)	(62,725,000)
Intangible assets, gross	371,000,000	371,000,000
Intangible assets, net	303,450,000	308,275,000
HomeLink® | Homelink Technology
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	180,000,000	180,000,000
Finite-lived intangible assets, accumulated amortization	(52,500,000)	(48,750,000)
Finite-lived intangible assets, net	$ 127,500,000	$ 131,250,000
HomeLink® | Homelink Technology | Minimum [Member]
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	12 years	12 years
HomeLink® | Existing Customer Platforms
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 43,000,000	$ 43,000,000
Finite-lived intangible assets, accumulated amortization	(15,050,000)	(13,975,000)
Finite-lived intangible assets, net	$ 27,950,000	$ 29,025,000
Finite-lived intangible asset, useful life	10 years	10 years
HomeLink® | HomeLink Trade Names and Trademarks
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 52,000,000	$ 52,000,000
HomeLink® | Exclusive Licensing Agreement
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 96,000,000	$ 96,000,000
[1]	Note: The condensed consolidated balance sheet at December 31, 2016 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Investments (Schedule of Amorti

Investments (Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value of Investment Securities) (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	$ 559,645,625	$ 546,477,075
Cost	231,686,980	222,624,828
Unrealized Gains	6,880,406	5,209,434
Unrealized Losses	(419,421)	(918,703)
Market Value	238,147,965	226,915,559
Investments and Cash	797,793,590	773,392,634
Short-term Investments [Member] | Certificates of Deposit [Member]
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 [Member] | Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	17,017,432	14,003,644
Unrealized Gains	0	0
Unrealized Losses	(21,362)	(10,164)
Market Value	16,996,070	13,993,480
Short-term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost		26,326,674
Unrealized Gains		27,459
Unrealized Losses		(237,452)
Market Value	26,322,271	26,116,681
Short-term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	3,058,352	6,706,721
Unrealized Gains	0	0
Unrealized Losses	(3,632)	(8,339)
Market Value	3,054,720	6,698,382
Short-term Investments [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	262,742	212,653
Unrealized Gains	0	0
Unrealized Losses	0	0
Market Value	262,742	212,653
Short-term Investments [Member] | Mutual Funds – Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	26,458,425
Unrealized Gains	41,908
Unrealized Losses	(178,062)
Market Value	26,322,271
Long-Term Investments [Member] | Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	6,059,283	5,519,668
Unrealized Gains	0	661
Unrealized Losses	(9,093)	(9,539)
Market Value	6,050,190	5,510,790
Long-Term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost		27,329,164
Unrealized Gains		1,830,992
Unrealized Losses		(288,146)
Market Value		28,872,010
Long-Term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	10,823,853	1,955,292
Unrealized Gains	9,342	0
Unrealized Losses	(3,650)	(6,736)
Market Value	10,829,545	1,948,556
Long-Term Investments [Member] | Common Stocks [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	9,879,067	9,825,550
Unrealized Gains	3,613,008	3,349,962
Unrealized Losses	(186,812)	(326,505)
Market Value	13,305,263	12,849,007
Long-Term Investments [Member] | Mutual Funds – Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	27,382,364
Unrealized Gains	3,206,612
Unrealized Losses	(5,223)
Market Value	30,583,753
Long-Term Investments [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	745,462	745,462
Unrealized Gains	9,536	360
Unrealized Losses	(11,587)	(31,822)
Market Value	743,411	714,000
Fair Value, Inputs, Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	559,645,625	546,477,075
Investments and Cash	734,540,794	719,124,745
Fair Value, Inputs, Level 1 [Member] | Short-term Investments [Member] | Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	130,000,000	130,000,000
Fair Value, Inputs, Level 1 [Member] | Short-term Investments [Member] | Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 1 [Member] | Short-term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0
Fair Value, Inputs, Level 1 [Member] | Short-term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 1 [Member] | Short-term Investments [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	262,742	212,653
Fair Value, Inputs, Level 1 [Member] | Long-Term Investments [Member] | Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0
Fair Value, Inputs, Level 1 [Member] | Long-Term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value		28,872,010
Fair Value, Inputs, Level 1 [Member] | Long-Term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0
Fair Value, Inputs, Level 1 [Member] | Long-Term Investments [Member] | Common Stocks [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	13,305,263	12,849,007
Fair Value, Inputs, Level 1 [Member] | Long-Term Investments [Member] | Mutual Funds – Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	30,583,753
Fair Value, Inputs, Level 1 [Member] | Long-Term Investments [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	743,411	714,000
Fair Value, Inputs, Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	0	0
Investments and Cash	63,252,796	54,267,889
Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member] | Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member] | Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	16,996,070	13,993,480
Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	26,322,271	26,116,681
Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	3,054,720	6,698,382
Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 2 [Member] | Long-Term Investments [Member] | Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	6,050,190	5,510,790
Fair Value, Inputs, Level 2 [Member] | Long-Term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value		0
Fair Value, Inputs, Level 2 [Member] | Long-Term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	10,829,545	1,948,556
Fair Value, Inputs, Level 2 [Member] | Long-Term Investments [Member] | Common Stocks [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 2 [Member] | Long-Term Investments [Member] | Mutual Funds – Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0
Fair Value, Inputs, Level 2 [Member] | Long-Term Investments [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0
Fair Value, Inputs, Level 3 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	0	0
Investments and Cash	0	0
Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member] | Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member] | Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] | Long-Term Investments [Member] | Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] | Long-Term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value		0
Fair Value, Inputs, Level 3 [Member] | Long-Term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] | Long-Term Investments [Member] | Common Stocks [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] | Long-Term Investments [Member] | Mutual Funds – Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0
Fair Value, Inputs, Level 3 [Member] | Long-Term Investments [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	$ 0	$ 0

Investments (Schedule of Unreal

Investments (Schedule of Unrealized Loss on Investments) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Investments [Abstract]
Aggregate Unrealized Losses, Less than one year	$ 321,258	$ 767,612
Aggregate Fair Value, Less than one year	51,576,425	55,574,292
Aggregate Unrealized Losses, Greater than one year	98,163	151,091
Aggregate Fair Value, Greater than one year	269,524	358,120
Aggregate Unrealized Losses, Total	419,421	918,703
Aggregate Fair Value, Total	51,845,949	55,932,412
Equity investment losses were considered to be other than temporary	$ 0	$ 0

Investments (Investments Classi

Investments (Investments Classified by Contractual Maturity Date) (Details) - Fixed Income Securities [Member]	Mar. 31, 2017USD ($)
Schedule of Available-for-sale Securities [Line Items]
Due within one year	$ 150,050,790
Due between one and five years	17,623,180
Due over five years	0
Total	$ 167,673,970

Inventories (Schedule of Invent

Inventories (Schedule of Inventories) (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 122,534,856	$ 115,099,569
Work-in-process	33,896,522	32,509,368
Finished goods	40,656,873	41,702,500
Total Inventory	$ 197,088,251	$ 189,311,437	[1]
[1]	Note: The condensed consolidated balance sheet at December 31, 2016 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, 2017	Mar. 31, 2016
Numerators [Abstract]
Numerator for both basic and diluted EPS, net income	$ 97,556,741	$ 80,279,994
Denominators [Abstract]
Denominator for basic EPS, weighted-average shares outstanding	287,408,900	289,210,621
Potentially dilutive shares resulting from stock plans	4,070,938	2,105,732
Denominator for diluted EPS	291,479,838	291,316,353
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive	2,311	7,866,330

Stock-Based Compensation Plan36

Stock-Based Compensation Plans (Narrative) (Details)	3 Months Ended
	Mar. 31, 2017USD ($)planshares	Mar. 31, 2016USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense for share-based payments | $	$ 3,484,240	$ 4,022,382
Compensation cost capitalized as part of inventory | $	$ 226,119	$ 292,187
Employee Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (in shares) | shares	24,000,000
Unrecognized compensation cost | $	$ 15,329,604
Employee Stock Option Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period	1 year
Option expiration period	5 years
Employee Stock Option Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period	5 years
Option expiration period	7 years
Non-Employee Director Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period	6 months
Option expiration period	10 years
Number of shares authorized (in shares) | shares	1,000,000
Unrecognized compensation cost | $	$ 0
Options granted (in shares) | shares	371,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares approved (in shares) | shares	2,000,000
ESPP discount rate	85.00%
Shares granted (in shares) | shares	659,810
ESPP discount rate recognized as compensation expense	15.00%
Restricted Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares) | shares	9,000,000
Restricted period, maximum, in years	10 years
Unearned stock-based compensation | $	$ 14,924,917
Amortization expense | $	$ 940,811
Equity Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans (in plans) | plan	4
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans (in plans) | plan	2

Stock-Based Compensation Plan37

Stock-Based Compensation Plans (Weighted-Average Assumptions for the ESOP) (Details) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Dividend yield	2.18%	2.15%
Expected volatility	29.81%	34.53%
Risk-free interest rate	2.10%	1.38%
Expected term of options	4 years 33 days	4 years 2 months 5 days
Weighted-avg. grant-date fair value (in dollars per share)	$ 4.51	$ 3.67

Comprehensive Income (AOCI Roll

Comprehensive Income (AOCI Rollforward) (Details) - USD ($)		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[1]	$ 1,910,424,234
Comprehensive Income		99,573,280	$ 79,518,748
Balance at end of period		1,974,771,538
Accumulated other comprehensive income (loss), end of period		745,234	(1,892,082)
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(2,862,999)	(44,909)
Other Comprehensive income (loss) before reclassifications		188,590	324,844
Comprehensive Income		188,590	324,844
Balance at end of period		(2,674,409)	279,935
Unrealized gains on available-for-sale securities:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		2,788,975	829,907
Other Comprehensive income (loss) before reclassifications		1,575,383	(508,348)
Amounts reclassified from accumulated other comprehensive income		(164,718)	300,771
Comprehensive Income		1,410,665	(207,577)
Balance at end of period		4,199,640	622,330
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(1,197,281)	(1,915,834)
Other Comprehensive income (loss) before reclassifications		147,318	(1,237,475)
Amounts reclassified from accumulated other comprehensive income		269,966	358,962
Comprehensive Income		417,284	(878,513)
Balance at end of period		$ (779,997)	$ (2,794,347)
[1]	Note: The condensed consolidated balance sheet at December 31, 2016 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, 2017	Mar. 31, 2016
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	$ (37,308,163)	$ (39,289,618)
Amounts Reclassified from Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period	(105,248)	(659,733)
Amounts Reclassified from Other Comprehensive Income | Unrealized gains on available-for-sale securities:
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss) on sale of securities	253,413	(462,724)
Provision for Income Taxes	(88,695)	161,953
Total reclassifications for the period	164,718	(300,771)
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	(415,333)	(552,250)
Provision for Income Taxes	145,367	193,288
Total reclassifications for the period	$ (269,966)	$ (358,962)

Debt and Financing Arrangemen40

Debt and Financing Arrangements (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016		Oct. 01, 2014	Sep. 27, 2013
Debt Instrument [Line Items]
Long-term debt	$ 36,250,000		$ 178,125,000	[1]
Financial Liabilities:
Effect of 1% in increase on borrowing rate (less than)	100,000
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Amount of hedged item					$ 150,000,000
Notional amount of derivative	150,000,000		150,000,000		$ 150,000,000
Fixed interest rate of derivative					1.89%
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Interest Rate Swap Asset	0		0
Financial Liabilities:
Interest Rate Swap Liability (Other Accrued Liabilities)	1,199,995		$ 1,841,970
Other, Net [Member]
Debt Instrument [Line Items]
Payments of financing costs	900,000	$ 900,000
Other, Net [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Interest expense	$ 400,000	$ 600,000
LIBOR Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.99%
Term Loan and Revolving Facility [Member]
Debt Instrument [Line Items]
Partial repayment of debt	$ 41,900,000
Revolving Facility [Member]
Debt Instrument [Line Items]
Partial repayment of debt	40,000,000
Credit Agreement [Member]
Debt Instrument [Line Items]
Short-term debt	100,000,000
Credit Agreement [Member]
Debt Instrument [Line Items]
Additional principal amount available						$ 75,000,000
Revolving Facility [Member]
Debt Instrument [Line Items]
Principal amount						150,000,000
Long-term debt	20,800,000
Available borrowing capacity	129,200,000
Term Loan [Member]
Debt Instrument [Line Items]
Principal amount						150,000,000
Long-term debt	123,800,000
Annual principal repayments	$ 7,500,000
Swing Loans [Member]
Debt Instrument [Line Items]
Additional principal amount available						20,000,000
Letters of Credit [Member]
Debt Instrument [Line Items]
Additional principal amount available						$ 20,000,000
[1]	Note: The condensed consolidated balance sheet at December 31, 2016 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.

Equity (Details)

Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016
Equity [Abstract]
Common stock issued under stock compensation plan (in shares)	1,511,640
Stock repurchased (in shares)	1,473,403
Net decrease in period (in shares)	38,237
Increase in quarterly cash dividend rate (in dollars per share)		$ 0.005
Dividends declared (in dollars per share)	$ 0.09		$ 0.085
Dividends declared	$ 25.9

Segment Reporting (Schedule Of

Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Revenue	$ 453,535,250	$ 405,567,786
Income from operations	134,427,120	120,848,990
Automotive Products
Segment Reporting Information [Line Items]
Revenue	445,652,575	393,968,947
Income from operations	132,504,957	115,980,617
Other
Segment Reporting Information [Line Items]
Revenue	7,882,675	11,598,839
Income from operations	$ 1,922,163	$ 4,868,373

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate	27.70%	32.90%
Favorable discrete items	$ 5.6
Change in tax method	3.8
Recognized a discrete tax benefit	$ 1.8	$ 1.8