Gentex (GNTX) 10-Q 4 Nov 16 2016 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 20, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	GENTEX CORPORATION
Entity Central Index Key	355,811
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Amendment Flag	false
Trading Symbol	gntx
Entity Common Stock, Shares Outstanding		286,509,623

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Balance Sheets - USD ($)	Sep. 30, 2016	Dec. 31, 2015	[1]
CURRENT ASSETS
Cash and cash equivalents	$ 534,518,281	$ 551,557,527
Short-term investments	152,235,753	4,547,355
Accounts receivable, net	229,236,789	195,969,400
Inventories	179,353,603	174,695,411
Prepaid expenses and other	13,471,694	57,239,099
Total current assets	1,108,816,120	984,008,792
PLANT AND EQUIPMENT—NET	450,781,365	412,720,270
OTHER ASSETS
Goodwill	307,365,845	307,365,845
Long-term investments	57,458,514	95,156,539
Intangible Assets, net	313,100,000	327,575,000
Patents and other assets, net	20,751,828	21,846,482
Total other assets	698,676,187	751,943,866
Total assets	2,258,273,672	2,148,672,928
CURRENT LIABILITIES
Accounts payable	71,000,819	66,353,774
Accrued liabilities	85,478,444	64,652,772
Total current liabilities	156,479,263	131,006,546
LONG TERM DEBT	195,000,000	225,625,000
DEFERRED INCOME TAXES	50,529,019	69,524,621
TOTAL LIABILITIES	402,008,282	426,156,167
SHAREHOLDERS’ INVESTMENT
Common stock	17,275,776	17,480,281
Additional paid-in capital	655,290,470	596,782,695
Retained earnings	1,184,141,924	1,109,384,621
Accumulated other comprehensive income	(442,780)	(1,130,836)
Total shareholders’ investment	1,856,265,390	1,722,516,761
Total liabilities and shareholders’ investment	$ 2,258,273,672	$ 2,148,672,928
[1]	Note: The condensed consolidated balance sheet at December 31, 2015 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Unaudited Condensed Consolidat3

Unaudited Condensed Consolidated Statements of Income - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
NET SALES	$ 429,643,276	$ 389,829,139	$ 1,259,011,840	$ 1,138,025,071
COST OF GOODS SOLD	255,821,376	237,932,439	759,726,593	697,492,531
Gross profit	173,821,900	151,896,700	499,285,247	440,532,540
OPERATING EXPENSES:
Engineering, research and development	23,585,115	21,505,461	69,748,112	65,408,256
Selling, general & administrative	16,024,504	14,128,619	45,730,143	43,020,328
Total operating expenses	39,609,619	35,634,080	115,478,255	108,428,584
Income from operations	134,212,281	116,262,620	383,806,992	332,103,956
OTHER INCOME (LOSS)
Investment income	916,556	495,468	2,480,699	1,861,545
Other Income (Loss), net	(800,855)	(710,346)	(4,781,387)	950,304
Total Other Income (Loss)	115,701	(214,878)	(2,300,688)	2,811,849
Income before provision for income taxes	134,327,982	116,047,742	381,506,304	334,915,805
PROVISION FOR INCOME TAXES	42,263,336	37,715,317	122,676,422	104,841,502
NET INCOME	$ 92,064,646	$ 78,332,425	$ 258,829,882	$ 230,074,303
EARNINGS PER SHARE:
Basic (in dollars per share)	$ 0.32	$ 0.27	$ 0.90	$ 0.78
Diluted (in dollars per share)	0.32	0.27	0.89	0.77
Cash Dividends Declared per Share (in dollars per share)	$ 0.09	$ 0.085	$ 0.265	$ 0.25

Unaudited Condensed Consolidat4

Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 92,064,646	$ 78,332,425	$ 258,829,882	$ 230,074,303
Other comprehensive income (loss) before tax:
Foreign currency translation adjustments	162,343	(396,686)	(1,266,636)	(1,038,892)
Unrealized gains (losses) on derivatives	1,070,229	(1,275,655)	(401,803)	(3,143,576)
Unrealized gains (losses) on available-for sales securities, net	3,345,885	(11,808,718)	3,409,021	(15,372,962)
Other comprehensive income (loss), before tax	4,578,457	(13,481,059)	1,740,582	(19,555,430)
Expense (Benefit) for income taxes related to components of other comprehensive income (loss)	1,545,640	(4,579,531)	1,052,527	(6,480,789)
Other comprehensive income (loss), net of tax	3,032,817	(8,901,528)	688,055	(13,074,641)
Comprehensive Income	$ 95,097,463	$ 69,430,897	$ 259,517,937	$ 216,999,662

Unaudited Condensed Consolidat5

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2016		Sep. 30, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 258,829,882		$ 230,074,303
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	68,853,761		63,709,095
Gain on disposal of assets	(10,900)		(18,052)
Loss on disposal of assets	796,234		360,659
Gain on sale of investments	(3,170,455)		(8,390,451)
Loss on sale of investments	3,512,544		1,828,617
Deferred income taxes	2,204,030		(10,836,858)
Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock	14,503,307		16,534,607
Excess tax benefits from stock-based compensation	(3,391,853)		(2,411,583)
Change in operating assets and liabilities:
Accounts receivable, net	(33,267,389)		(40,194,912)
Inventories	(4,658,192)		(22,846,177)
Prepaid expenses and other	21,515,247		9,106,066
Accounts payable	4,647,045		12,435,275
Accrued liabilities, excluding dividends declared	22,661,540		33,810,991
Net cash provided by operating activities	353,024,801		283,161,580
Activity in available-for-sale securities:
Sales proceeds	75,741,184		45,787,794
Purchases	(182,664,625)		(34,380,942)
Plant and equipment additions	(91,497,229)		(62,282,827)
Proceeds from sale of plant and equipment	516,667		4
Decrease in other assets	(2,416,610)		(1,931,566)
Net cash used for investing activities	(200,320,613)		(52,807,537)
CASH FLOWS USED FOR FINANCING ACTIVITIES:
Repayment of long-term debt	(30,625,000)		(30,625,000)
Issuance of common stock from stock plan transactions	55,449,028		20,008,358
Cash dividends paid	(75,217,692)		(72,150,137)
Repurchases of common stock	(122,741,623)		(82,900,454)
Excess tax benefits from stock-based compensation	3,391,853		2,411,583
Net cash used for financing activities	(169,743,434)		(163,255,650)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(17,039,246)		67,098,393
CASH AND CASH EQUIVALENTS, beginning of period	551,557,527	[1]	497,429,804
CASH AND CASH EQUIVALENTS, end of period	$ 534,518,281		$ 564,528,197
[1]	Note: The condensed consolidated balance sheet at December 31, 2015 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2016
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 2015 annual report on Form 10-K. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all adjustments, consisting of only a normal and recurring nature, necessary to present fairly the financial position of the Company as of September 30, 2016 , and the results of operations and cash flows for the interim periods presented.

Adoption of New Accounting Stan

Adoption of New Accounting Standards	9 Months Ended
	Sep. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Adoption of New Accounting Standards	Adoption of New Accounting Standards In May 2014 the Financial Accounting Standards Board (FASB) issued the Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606) , that will supersede nearly all existing revenue recognition guidance under US GAAP. The core principle of the guidance is that an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The standard was to originally be effective for public entities for annual and interim periods beginning after December 15, 2016. On July 9, 2015 the FASB decided to defer by one year the effective dates of the new standard for both public and nonpublic entities reporting under US GAAP. Early adoption would be permitted for all entities, but not before the original public entity effective date (i.e. annual and interim periods beginning after December 15, 2016). Entities can choose to apply the standard using either the full retrospective approach or a modified retrospective approach. Entities electing the full retrospective adoption will apply the standard to each period presented in the financial statements. This means that entities will have to apply the new guidance as if it had been in effect since the inception of all its contracts with customers presented in the financial statements. Entities that elect the modified retrospective approach will apply the guidance retrospectively only to the most current period presented in the financial statements. This means that entities will have to recognize the cumulative effect of initially applying the new standard as an adjustment to the opening balance of retained earnings at the date of initial application. The new revenue standard will be applied to contracts that are in progress at the date of initial application. The Company is currently evaluating which adoption method it plans to use and is assessing the potential effect the new standard will have on its consolidated financial statements. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes , requiring all deferred tax assets and liabilities, and any related valuation allowance, to be classified as non-current on the balance sheet instead of separating deferred taxes into current and non-current amounts. The classification change for all deferred taxes as non-current simplifies entities’ processes as it eliminates the need to separately identify the net current and net non-current deferred tax asset or liability in each jurisdiction and allocate valuation allowances. The guidance is effective for annual periods beginning after December 15, 2016. The Company adopted ASU No. 2015-17 in the first quarter of 2016 on a prospective basis. As such, prior periods were not retrospectively adjusted. Adoption of this standard during the quarter ended March 31, 2016 resulted in the reclassification of approximately $27 million of deferred income taxes from current assets to non-current liabilities. 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, Stock Compensation , which identifies areas for simplification involving several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, an option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the statement of cash flows. The guidance will be effective for the fiscal year beginning after December 15, 2016, including interim periods within that year. The Company is in the process of assessing the potential effect the new standard will have on its consolidated financial statements. 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	9 Months Ended
	Sep. 30, 2016
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, 2015 and September 30, 2016 was $307.4 million . In addition to annual impairment testing, which is performed as of the first day of the fourth quarter, the Company continuously monitors for events and circumstances that could negatively impact the key assumptions in determining fair value thus resulting in the need for interim impairment testing, including long-term revenue growth projections, profitability, discount rates, recent market valuations from transactions by comparable companies, volatility in the Company's market capitalization, and general industry, market and macroeconomic conditions. No such events or circumstances in the most recently completed quarter indicated the need for interim impairment testing. The patents and intangible assets and related change in carrying values are set forth in the tables below: As of September 30, 2016 : Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 32,302,452 $ (15,791,045 ) $ 16,511,407 various Other Intangible Assets HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (45,000,000 ) 135,000,000 12 years Existing Customer Platforms 43,000,000 (12,900,000 ) 30,100,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total Other Intangible Assets $ 371,000,000 $ (57,900,000 ) $ 313,100,000 Total Patents & Other Intangible Assets $ 403,302,452 $ (73,691,045 ) $ 329,611,407 As of December 31, 2015: Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 31,873,665 $ (13,890,202 ) $ 17,983,463 various HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (33,750,000 ) $ 146,250,000 12 years Existing Customer Platforms 43,000,000 (9,675,000 ) $ 33,325,000 10 years Exclusive Licensing Agreement 96,000,000 — $ 96,000,000 Indefinite Total other identifiable intangible assets $ 371,000,000 $ (43,425,000 ) $ 327,575,000 Total Patents & Other Intangible Assets $ 402,873,665 $ (57,315,202 ) $ 345,558,463 Amortization expense on patents and intangible assets was approximately $5.6 million and $16.7 million during the three and nine month periods ended September 30, 2016 , respectively, compared to approximately $5.5 million and $16.5 million for the same periods ended September 30, 2015 , respectively. Excluding the impact of any future acquisitions, the Company continues to estimate amortization expense for each of the years ended December 31, 2016, 2017, 2018, 2019 and 2020 to be approximately $22 million annually.

Investments

Investments	9 Months Ended
	Sep. 30, 2016
Investments [Abstract]
Investments	Investments The Company follows the provisions of ASC 820, “Fair Value Measurements and Disclosures” for its financial assets and liabilities, and for its non-financial assets and liabilities subject to fair value measurements. ASC 820 provides a framework for measuring the fair value of assets and liabilities. This framework is intended to provide increased consistency in how fair value determinations are made under various existing accounting standards that permit, or in some cases, require estimates of fair-market value. This standard also expanded financial statement disclosure requirements about a company’s use of fair-value measurements, including the effect of such measure on earnings. The cost of securities sold is based on the specific identification method. The Company’s investment securities (common stocks and mutual funds) are classified as available for sale and are stated at fair value based on quoted market prices, and as such are classified as Level 1 assets. 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 September 30, 2016 , and December 31, 2015 : As of September 30, 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 September 30, 2016 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 534,518,281 $ 534,518,281 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Government Securities 10,010,610 — 10,010,610 — Mutual Funds 5,334,512 — 5,334,512 — Corporate Bonds 6,765,414 — 6,765,414 — Other 125,217 125,217 — — Long-Term Investments: Corporate Bonds 1,968,094 — 1,968,094 — Common Stocks 13,693,634 13,693,634 — — Mutual Funds – Equity 41,404,005 41,404,005 — — Preferred Stock 392,781 392,781 — $ — Total $ 744,212,548 $ 720,133,918 $ 24,078,630 $ — As of December 31, 2015 : Fair Value Measurements at Reporting Date Using Total as of Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Description December 31, 2015 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 551,557,527 $ 551,557,527 $ — $ — Short-Term Investments: Government Securities 3,010,860 — 3,010,860 — Corporate Bonds 1,512,015 — 1,512,015 — Other 24,480 24,480 — — Long-Term Investments: Common Stocks 20,454,804 20,454,804 — — Mutual Funds – Equity 74,701,735 74,701,735 — — Total $ 651,261,421 $ 646,738,546 $ 4,522,875 $ — The amortized cost, unrealized gains and losses, and market value of investment securities are shown as of September 30, 2016 , and December 31, 2015 : As of September 30, 2016 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities $ 10,011,046 $ 1,799 $ (2,235 ) $ 10,010,610 Mutual Funds 5,235,438 99,140 (66 ) 5,334,512 Corporate Bonds 6,773,386 — (7,972 ) 6,765,414 Other 125,217 — — 125,217 Long-Term Investments: Corporate Bonds 1,970,096 — (2,002 ) 1,968,094 Common Stocks 10,978,179 3,111,060 (395,605 ) 13,693,634 Mutual Funds – Equity 39,536,844 2,206,543 (339,382 ) 41,404,005 Preferred Stock 378,260 14,521 — 392,781 Total $ 205,008,466 $ 5,433,063 $ (747,262 ) $ 209,694,267 As of December 31, 2015 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Government Securities $ 3,013,482 $ — $ (2,622 ) $ 3,010,860 Corporate Bonds 1,512,405 — (390 ) 1,512,015 Other 24,480 — — 24,480 Long-Term Investments: Common Stocks 17,395,641 4,078,912 (1,019,749 ) 20,454,804 Mutual Funds – Equity 76,481,106 2,067,399 (3,846,770 ) 74,701,735 Total $ 98,427,114 $ 6,146,311 $ (4,869,531 ) $ 99,703,894 Unrealized losses on investments as of September 30, 2016 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 506,734 $ 31,401,343 Greater than one year 240,528 1,481,420 Total $ 747,262 $ 32,882,763 Unrealized losses on investments as of December 31, 2015 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 4,869,531 $ 65,440,181 Greater than one year — — Total $ 4,869,531 $ 65,440,181 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. Fixed income securities as of September 30, 2016, have contractual maturities as follows: Due within one year $ 146,776,024 Due between one and five years 1,968,094 Due over five years — 148,744,118

Inventories

Inventories	9 Months Ended
	Sep. 30, 2016
Inventory Disclosure [Abstract]
Inventories	Inventories consisted of the following at the respective balance sheet dates: September 30, 2016 December 31, 2015 Raw materials $ 108,033,204 $ 110,683,958 Work-in-process 31,230,322 27,077,220 Finished goods 40,090,077 36,934,233 Total Inventory $ 179,353,603 $ 174,695,411

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The following table reconciles the numerators and denominators used in the calculation of basic and diluted earnings per share (EPS): Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Numerators: Numerator for both basic and diluted EPS, net income $ 92,064,646 $ 78,332,425 $ 258,829,882 $ 230,074,303 Denominators: Denominator for basic EPS, weighted-average shares outstanding 287,736,638 292,589,866 288,466,905 293,742,028 Potentially dilutive shares resulting from stock plans 2,717,187 2,787,612 2,557,758 3,252,544 Denominator for diluted EPS 290,453,825 295,377,478 291,024,663 296,994,572 Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive 1,818,032 3,756,396 4,193,947 1,611,900

Stock-Based Compensation Plans

Stock-Based Compensation Plans	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans As of September 30, 2016 , 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, 2015 , for additional information related to these stock-based compensation plans. The Company recognized compensation expense for share-based payments of $3,724,780 and $11,558,462 for the three and nine months ended September 30, 2016 , respectively and $4,404,297 and $13,979,297 for the three and nine months ended September 30, 2015 , respectively. Compensation cost capitalized as part of inventory as of September 30, 2016 and 2015 was $317,315 and $279,903 , 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 September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Dividend Yield (1) 2.19 % 2.12 % 2.17 % 2.13 % Expected volatility (2) 32.19 % 35.81 % 33.62 % 36.10 % Risk-free interest rate (3) 1.14 % 1.37 % 1.18 % 1.56 % Expected term of options (years) (4) 4.29 4.31 4.26 4.97 Weighted-avg. grant date fair value $3.91 $3.94 $3.74 $4.47 (1) Represents the Company’s estimated cash dividend yield over the expected term of option grant. (2) Amount is determined based on analysis of historical price volatility of the Company’s common stock. The expected volatility is based on the daily percentage change in the price of the stock over a period equal to the expected term of the option grant. (3) Represents the U.S. Treasury yield over the expected term of the option grant. (4) Represents the period of time that options granted are expected to be outstanding. Based on analysis of historical option exercise activity, the Company has determined that all employee groups exhibit similar exercise and post-vesting termination behavior. Under the employee stock option plan, the option exercise price equals the stock’s market price on date of grant. The options vest after one to five years, and expire after five to seven years. As of September 30, 2016 , there was $18,589,743 of unrecognized compensation cost related to share-based payments which is expected to be recognized over the vesting periods. Non-employee Director Stock Option Plan The Company has a non-employee director stock option plan covering 1,000,000 shares of common stock. As of September 30, 2016 , there was $66,324 of 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 September 30, 2016 . Under the non-employee director plan, the option exercise price equals the stock’s market price on the date of grant. The options vest after six months , and expire after ten years . Employee Stock Purchase Plan The Company has an employee stock purchase plan covering 2,000,000 shares of common stock. Under the plan, the Company sells shares at 85% of the stock’s market price at date of purchase. Under ASC 718, the 15% discounted value is recognized as compensation expense. As of September 30, 2016 , the Company has granted 585,668 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 September 30, 2016 , the Company had unearned stock-based compensation of $11,816,334 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 and nine months ended September 30, 2016 was $1,001,100 and $2,944,845 .

Comprehensive Income

Comprehensive Income	9 Months Ended
	Sep. 30, 2016
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 September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Foreign currency translation adjustments: Balance at beginning of period $ (1,473,888 ) $ 761,692 $ (44,909 ) $ 1,403,899 Other Comprehensive (loss) income before reclassifications 162,343 (396,685 ) (1,266,636 ) (1,038,892 ) Net current-period change 162,343 (396,685 ) (1,266,636 ) (1,038,892 ) Balance at end of period (1,311,545 ) 365,007 (1,311,545 ) 365,007 Unrealized gains (losses) on available-for-sale securities: Balance at beginning of period 870,945 8,551,564 829,907 10,868,322 Other Comprehensive income (loss) before reclassifications 2,269,315 (6,353,685 ) 1,993,505 (5,727,233 ) Amounts reclassified from accumulated other comprehensive income (94,489 ) (1,321,982 ) 222,359 (4,265,192 ) Net current-period change 2,174,826 (7,675,667 ) 2,215,864 (9,992,425 ) Balance at end of period 3,045,771 875,897 3,045,771 875,897 Unrealized gains (losses) on derivatives: Balance at beginning of period (2,872,655 ) (2,173,354 ) (1,915,834 ) (959,206 ) Other comprehensive income (loss) before reclassifications 353,397 (1,113,648 ) (1,321,890 ) (2,327,796 ) Amounts reclassified from accumulated other comprehensive income 342,252 284,472 1,060,718 284,472 Net current-period change 695,649 (829,176 ) (261,172 ) (2,043,324 ) Balance at end of period (2,177,006 ) (3,002,530 ) (2,177,006 ) (3,002,530 ) Accumulated other comprehensive income (loss), end of period $ (442,780 ) $ (1,761,626 ) $ (442,780 ) $ (1,761,626 ) The following table presents details of reclassifications out of other comprehensive income for the three and nine months ended September 30, 2016 and 2015 . Details about Accumulated Other Comprehensive Income Components Amounts Reclassified from Other Comprehensive Income Affected Line item in the Statement of Consolidated Income Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Unrealized gains on available-for-sale securities Realized gain (loss) on sale of securities $ 145,367 $ 2,033,819 $ (342,090 ) $ 6,561,834 Other, net Provision for Income Taxes (50,878 ) (711,837 ) 119,732 (2,296,642 ) Provision for Income Taxes $ 94,489 $ 1,321,982 $ (222,358 ) $ 4,265,192 Net of tax Unrealized gains (losses) on derivatives Realized loss on interest rate swap $ (526,542 ) $ (437,650 ) $ (1,631,875 ) $ (437,650 ) Other, net Provision for Income Taxes 184,290 153,178 571,156 153,178 Provision for Income Taxes $ (342,252 ) $ (284,472 ) $ (1,060,719 ) $ (284,472 ) Net of tax Total reclassifications for the period $ (247,763 ) $ 1,037,510 $ (1,283,077 ) $ 3,980,720 Net of tax

Debt and Financing Arrangements

Debt and Financing Arrangements	9 Months Ended
	Sep. 30, 2016
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 and nine months ended September 30, 2016 , the Company made principal repayments of $11.8 million and $30.6 million respectively, plus accrued interest, on the Term Loan and Revolver. The aforementioned payments include a payment made by the Company of $15.0 million on the Revolver during the first quarter of 2016 and a payment of $10.0 million on the Revolver during the third quarter of 2016, which was in addition to scheduled amounts due. The Company used cash and cash equivalents to fund the payments. As of September 30, 2016 , $75.7 million was outstanding on the Revolver with availability of an additional $74.3 million . Under current terms of the Term Loan, the Company will make principal repayments of $7.5 million annually through the maturity date of the Term Loan. As of September 30, 2016 , $127.5 million was outstanding under the Term Loan. As of September 30, 2016 , the borrowing rate on both its Term Loan and Revolver are derived from the one month LIBOR, and based on the Company's leverage ratio as of September 30, 2016 , the interest rate on its borrowings is equal to 1.53% . 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 $0.8 million and $2.5 million during the three and nine months ended September 30, 2016 , respectively, and $0.8 million and $2.4 million during the three and nine months ended September 30, 2015 . The Credit Agreement contains customary representations and warranties and certain covenants that place certain limitations on the Company. As of September 30, 2016 , 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 $0.5 million and $1.6 million during the three and nine months ended September 30, 2016 , respectively, and $0.5 million during both the three and nine months ended September 30, 2015 . Notwithstanding the terms of the interest rate swap transaction, the Company is ultimately obligated for all amounts due and payable under its existing Credit Agreement. The notional amount of the Company's derivative instruments are as follows: September 30, 2016 December 31, 2015 Interest Rate swap $ 150,000,000 $ 150,000,000 The following table sets forth financial assets and liabilities measured at fair value related to the interest rate swap agreement and the respective pricing levels to which the fair value measurements are classified within the fair value hierarchy. The Company uses the market approach to derive the value of its level 2 fair value measurements. Interest rate swaps are valued using publicized swap curves. Fair Value Measurements Quoted Prices with Other Observable Inputs (Level 2) September 30, 2016 December 31, 2015 Financial assets: Interest Rate Swap Asset $ — $ — Financial Liabilities: Interest Rate Swap Liability (Other Accrued Liabilities) $ 3,349,240 $ 2,947,438 Based on loan balances as of September 30, 2016 and the effective date of July 31, 2015 of the interest rate swap, a one percent increase in the Company's borrowing rate would increase net interest expense paid by the Company on its borrowings by approximately $0.5 million dollars on an annual basis.

Equity

Equity	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Equity	Equity The decrease in common stock during the nine months ended September 30, 2016 , was primarily due to share repurchases of 8,041,358 shares pursuant to the Company's previously announced share repurchase plan, which was partially offset by the issuance of 4,632,945 shares of the Company’s common stock under the Company’s stock-based compensation plans for a net decrease of 3,408,413 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 second and third quarters of 2016 as compared to a cash dividend of $.085 per share during the first quarter of 2016. The third quarter 2016 dividend of $25.9 million , was declared on August 31, 2016 , and was paid on October 19, 2016 .

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies The Company is periodically involved in legal proceedings, legal actions and claims arising in the normal course of business, including proceedings relating to product liability, intellectual property, safety and health, employment and other matters. Such matters are subject to many uncertainties and outcomes are not predictable. The Company does not believe, however, that at the current time any of these matters constitute material pending legal proceedings that will have a material adverse effect on the financial position or future results of operations of the Company.

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2016
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 automotive mirrors with and without electronic features; and other electronics. The Company also develops and manufactures variably dimming windows for the aerospace industry and fire protection products for the commercial construction industry, which are combined into the "Other" segment shown below. Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Revenue: Automotive Products $ 419,793,577 $ 379,889,957 $ 1,228,165,639 $ 1,111,009,546 Other 9,849,699 9,939,182 30,846,201 27,015,525 Total $ 429,643,276 $ 389,829,139 $ 1,259,011,840 $ 1,138,025,071 Income from operations: Automotive Products $ 130,567,201 $ 112,238,938 $ 372,119,627 $ 322,289,461 Other 3,645,080 4,023,682 11,687,365 9,814,495 Total $ 134,212,281 $ 116,262,620 $ 383,806,992 $ 332,103,956

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate was 32.2% in the nine months ended September 30, 2016 compared to 31.3% for the same period in 2015. Effective tax rates for these quarters differ from statutory federal income tax rates, primarily due to the domestic manufacturing deduction, provisions for state and local income taxes and permanent tax differences. The increase in the effective tax rate for the nine months ended September 30, 2016 compared to the same period of 2015 is primarily due to the reversal of $3.9 million of the uncertain tax position related to the incremental research and development tax credits as a result of the Internal Revenue Service concluding audits for the Company’s amended filings for calendar years 2010 through 2012, in the first quarter of 2015.

Adoption of New Accounting St19

Adoption of New Accounting Standards (Policies)	9 Months Ended
	Sep. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Adoption of new Accounting Standards	Adoption of New Accounting Standards In May 2014 the Financial Accounting Standards Board (FASB) issued the Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606) , that will supersede nearly all existing revenue recognition guidance under US GAAP. The core principle of the guidance is that an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The standard was to originally be effective for public entities for annual and interim periods beginning after December 15, 2016. On July 9, 2015 the FASB decided to defer by one year the effective dates of the new standard for both public and nonpublic entities reporting under US GAAP. Early adoption would be permitted for all entities, but not before the original public entity effective date (i.e. annual and interim periods beginning after December 15, 2016). Entities can choose to apply the standard using either the full retrospective approach or a modified retrospective approach. Entities electing the full retrospective adoption will apply the standard to each period presented in the financial statements. This means that entities will have to apply the new guidance as if it had been in effect since the inception of all its contracts with customers presented in the financial statements. Entities that elect the modified retrospective approach will apply the guidance retrospectively only to the most current period presented in the financial statements. This means that entities will have to recognize the cumulative effect of initially applying the new standard as an adjustment to the opening balance of retained earnings at the date of initial application. The new revenue standard will be applied to contracts that are in progress at the date of initial application. The Company is currently evaluating which adoption method it plans to use and is assessing the potential effect the new standard will have on its consolidated financial statements. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes , requiring all deferred tax assets and liabilities, and any related valuation allowance, to be classified as non-current on the balance sheet instead of separating deferred taxes into current and non-current amounts. The classification change for all deferred taxes as non-current simplifies entities’ processes as it eliminates the need to separately identify the net current and net non-current deferred tax asset or liability in each jurisdiction and allocate valuation allowances. The guidance is effective for annual periods beginning after December 15, 2016. The Company adopted ASU No. 2015-17 in the first quarter of 2016 on a prospective basis. As such, prior periods were not retrospectively adjusted. Adoption of this standard during the quarter ended March 31, 2016 resulted in the reclassification of approximately $27 million of deferred income taxes from current assets to non-current liabilities. 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, Stock Compensation , which identifies areas for simplification involving several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, an option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the statement of cash flows. The guidance will be effective for the fiscal year beginning after December 15, 2016, including interim periods within that year. The Company is in the process of assessing the potential effect the new standard will have on its consolidated financial statements. 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)	9 Months Ended
	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	The patents and intangible assets and related change in carrying values are set forth in the tables below: As of September 30, 2016 : Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 32,302,452 $ (15,791,045 ) $ 16,511,407 various Other Intangible Assets HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (45,000,000 ) 135,000,000 12 years Existing Customer Platforms 43,000,000 (12,900,000 ) 30,100,000 10 years Exclusive Licensing Agreement 96,000,000 — 96,000,000 Indefinite Total Other Intangible Assets $ 371,000,000 $ (57,900,000 ) $ 313,100,000 Total Patents & Other Intangible Assets $ 403,302,452 $ (73,691,045 ) $ 329,611,407 As of December 31, 2015: Other Intangible Assets Gross Accumulated Amortization Net Assumed Useful Life Gentex Patents $ 31,873,665 $ (13,890,202 ) $ 17,983,463 various HomeLink ® Trade Names and Trademarks $ 52,000,000 $ — $ 52,000,000 Indefinite HomeLink ® Technology 180,000,000 (33,750,000 ) $ 146,250,000 12 years Existing Customer Platforms 43,000,000 (9,675,000 ) $ 33,325,000 10 years Exclusive Licensing Agreement 96,000,000 — $ 96,000,000 Indefinite Total other identifiable intangible assets $ 371,000,000 $ (43,425,000 ) $ 327,575,000 Total Patents & Other Intangible Assets $ 402,873,665 $ (57,315,202 ) $ 345,558,463

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2016
Investments [Abstract]
Investment Securities Stated at Fair Value	Assets or liabilities that have recurring fair value measurements are shown below as of September 30, 2016 , and December 31, 2015 : As of September 30, 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 September 30, 2016 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 534,518,281 $ 534,518,281 $ — $ — Short-Term Investments: Certificate of Deposit 130,000,000 130,000,000 — — Government Securities 10,010,610 — 10,010,610 — Mutual Funds 5,334,512 — 5,334,512 — Corporate Bonds 6,765,414 — 6,765,414 — Other 125,217 125,217 — — Long-Term Investments: Corporate Bonds 1,968,094 — 1,968,094 — Common Stocks 13,693,634 13,693,634 — — Mutual Funds – Equity 41,404,005 41,404,005 — — Preferred Stock 392,781 392,781 — $ — Total $ 744,212,548 $ 720,133,918 $ 24,078,630 $ — As of December 31, 2015 : Fair Value Measurements at Reporting Date Using Total as of Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Description December 31, 2015 (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 551,557,527 $ 551,557,527 $ — $ — Short-Term Investments: Government Securities 3,010,860 — 3,010,860 — Corporate Bonds 1,512,015 — 1,512,015 — Other 24,480 24,480 — — Long-Term Investments: Common Stocks 20,454,804 20,454,804 — — Mutual Funds – Equity 74,701,735 74,701,735 — — Total $ 651,261,421 $ 646,738,546 $ 4,522,875 $ —
Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value of Investment Securities	The amortized cost, unrealized gains and losses, and market value of investment securities are shown as of September 30, 2016 , and December 31, 2015 : As of September 30, 2016 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Certificate of Deposit $ 130,000,000 $ — $ — $ 130,000,000 Government Securities $ 10,011,046 $ 1,799 $ (2,235 ) $ 10,010,610 Mutual Funds 5,235,438 99,140 (66 ) 5,334,512 Corporate Bonds 6,773,386 — (7,972 ) 6,765,414 Other 125,217 — — 125,217 Long-Term Investments: Corporate Bonds 1,970,096 — (2,002 ) 1,968,094 Common Stocks 10,978,179 3,111,060 (395,605 ) 13,693,634 Mutual Funds – Equity 39,536,844 2,206,543 (339,382 ) 41,404,005 Preferred Stock 378,260 14,521 — 392,781 Total $ 205,008,466 $ 5,433,063 $ (747,262 ) $ 209,694,267 As of December 31, 2015 : Unrealized Cost Gains Losses Market Value Short-Term Investments: Government Securities $ 3,013,482 $ — $ (2,622 ) $ 3,010,860 Corporate Bonds 1,512,405 — (390 ) 1,512,015 Other 24,480 — — 24,480 Long-Term Investments: Common Stocks 17,395,641 4,078,912 (1,019,749 ) 20,454,804 Mutual Funds – Equity 76,481,106 2,067,399 (3,846,770 ) 74,701,735 Total $ 98,427,114 $ 6,146,311 $ (4,869,531 ) $ 99,703,894
Schedule of Unrealized Loss on Investments	Unrealized losses on investments as of September 30, 2016 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 506,734 $ 31,401,343 Greater than one year 240,528 1,481,420 Total $ 747,262 $ 32,882,763 Unrealized losses on investments as of December 31, 2015 , are as follows: Aggregate Unrealized Losses Aggregate Fair Value Less than one year $ 4,869,531 $ 65,440,181 Greater than one year — — Total $ 4,869,531 $ 65,440,181
Investments Classified by Contractual Maturity Date	Fixed income securities as of September 30, 2016, have contractual maturities as follows: Due within one year $ 146,776,024 Due between one and five years 1,968,094 Due over five years — 148,744,118

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2016
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories consisted of the following at the respective balance sheet dates: September 30, 2016 December 31, 2015 Raw materials $ 108,033,204 $ 110,683,958 Work-in-process 31,230,322 27,077,220 Finished goods 40,090,077 36,934,233 Total Inventory $ 179,353,603 $ 174,695,411

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Schedule of Earnings Per Share Basic And Diluted	The following table reconciles the numerators and denominators used in the calculation of basic and diluted earnings per share (EPS): Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Numerators: Numerator for both basic and diluted EPS, net income $ 92,064,646 $ 78,332,425 $ 258,829,882 $ 230,074,303 Denominators: Denominator for basic EPS, weighted-average shares outstanding 287,736,638 292,589,866 288,466,905 293,742,028 Potentially dilutive shares resulting from stock plans 2,717,187 2,787,612 2,557,758 3,252,544 Denominator for diluted EPS 290,453,825 295,377,478 291,024,663 296,994,572 Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive 1,818,032 3,756,396 4,193,947 1,611,900

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted-Average Assumptions For The Employee Stock Option Plan	The fair value of each option grant in the employee stock option plan was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions for the indicated periods: Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Dividend Yield (1) 2.19 % 2.12 % 2.17 % 2.13 % Expected volatility (2) 32.19 % 35.81 % 33.62 % 36.10 % Risk-free interest rate (3) 1.14 % 1.37 % 1.18 % 1.56 % Expected term of options (years) (4) 4.29 4.31 4.26 4.97 Weighted-avg. grant date fair value $3.91 $3.94 $3.74 $4.47 (1) Represents the Company’s estimated cash dividend yield over the expected term of option grant. (2) Amount is determined based on analysis of historical price volatility of the Company’s common stock. The expected volatility is based on the daily percentage change in the price of the stock over a period equal to the expected term of the option grant. (3) Represents the U.S. Treasury yield over the expected term of the option grant. (4) Represents the period of time that options granted are expected to be outstanding. Based on analysis of historical option exercise activity, the Company has determined that all employee groups exhibit similar exercise and post-vesting termination behavior.

Comprehensive Income (Tables)

Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Schedule of net changes in the Company's accumulated other comprehensive income by component	The following table presents the net changes in the Company's accumulated other comprehensive income (loss) by component: (All amounts shown are net of tax). Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Foreign currency translation adjustments: Balance at beginning of period $ (1,473,888 ) $ 761,692 $ (44,909 ) $ 1,403,899 Other Comprehensive (loss) income before reclassifications 162,343 (396,685 ) (1,266,636 ) (1,038,892 ) Net current-period change 162,343 (396,685 ) (1,266,636 ) (1,038,892 ) Balance at end of period (1,311,545 ) 365,007 (1,311,545 ) 365,007 Unrealized gains (losses) on available-for-sale securities: Balance at beginning of period 870,945 8,551,564 829,907 10,868,322 Other Comprehensive income (loss) before reclassifications 2,269,315 (6,353,685 ) 1,993,505 (5,727,233 ) Amounts reclassified from accumulated other comprehensive income (94,489 ) (1,321,982 ) 222,359 (4,265,192 ) Net current-period change 2,174,826 (7,675,667 ) 2,215,864 (9,992,425 ) Balance at end of period 3,045,771 875,897 3,045,771 875,897 Unrealized gains (losses) on derivatives: Balance at beginning of period (2,872,655 ) (2,173,354 ) (1,915,834 ) (959,206 ) Other comprehensive income (loss) before reclassifications 353,397 (1,113,648 ) (1,321,890 ) (2,327,796 ) Amounts reclassified from accumulated other comprehensive income 342,252 284,472 1,060,718 284,472 Net current-period change 695,649 (829,176 ) (261,172 ) (2,043,324 ) Balance at end of period (2,177,006 ) (3,002,530 ) (2,177,006 ) (3,002,530 ) Accumulated other comprehensive income (loss), end of period $ (442,780 ) $ (1,761,626 ) $ (442,780 ) $ (1,761,626 )
Schedule of reclassifications out of other comprehensive income	The following table presents details of reclassifications out of other comprehensive income for the three and nine months ended September 30, 2016 and 2015 . Details about Accumulated Other Comprehensive Income Components Amounts Reclassified from Other Comprehensive Income Affected Line item in the Statement of Consolidated Income Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Unrealized gains on available-for-sale securities Realized gain (loss) on sale of securities $ 145,367 $ 2,033,819 $ (342,090 ) $ 6,561,834 Other, net Provision for Income Taxes (50,878 ) (711,837 ) 119,732 (2,296,642 ) Provision for Income Taxes $ 94,489 $ 1,321,982 $ (222,358 ) $ 4,265,192 Net of tax Unrealized gains (losses) on derivatives Realized loss on interest rate swap $ (526,542 ) $ (437,650 ) $ (1,631,875 ) $ (437,650 ) Other, net Provision for Income Taxes 184,290 153,178 571,156 153,178 Provision for Income Taxes $ (342,252 ) $ (284,472 ) $ (1,060,719 ) $ (284,472 ) Net of tax Total reclassifications for the period $ (247,763 ) $ 1,037,510 $ (1,283,077 ) $ 3,980,720 Net of tax

Debt and Financing Arrangemen26

Debt and Financing Arrangements (Tables)	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Schedule of notional amount of the Company's derivative instruments	The notional amount of the Company's derivative instruments are as follows: September 30, 2016 December 31, 2015 Interest Rate swap $ 150,000,000 $ 150,000,000
Schedule of financial assets and liabilities measured at fair value in the consolidated balance sheets	The Company uses the market approach to derive the value of its level 2 fair value measurements. Interest rate swaps are valued using publicized swap curves. Fair Value Measurements Quoted Prices with Other Observable Inputs (Level 2) September 30, 2016 December 31, 2015 Financial assets: Interest Rate Swap Asset $ — $ — Financial Liabilities: Interest Rate Swap Liability (Other Accrued Liabilities) $ 3,349,240 $ 2,947,438

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Schedule of Automotive and Other Segment Reporting	The Company also develops and manufactures variably dimming windows for the aerospace industry and fire protection products for the commercial construction industry, which are combined into the "Other" segment shown below. Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Revenue: Automotive Products $ 419,793,577 $ 379,889,957 $ 1,228,165,639 $ 1,111,009,546 Other 9,849,699 9,939,182 30,846,201 27,015,525 Total $ 429,643,276 $ 389,829,139 $ 1,259,011,840 $ 1,138,025,071 Income from operations: Automotive Products $ 130,567,201 $ 112,238,938 $ 372,119,627 $ 322,289,461 Other 3,645,080 4,023,682 11,687,365 9,814,495 Total $ 134,212,281 $ 116,262,620 $ 383,806,992 $ 332,103,956

Adoption of New Accounting St28

Adoption of New Accounting Standards (Details) - USD ($)	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	[1]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred income taxes, non-current liabilities	$ 50,529,019		$ 69,524,621
Accounting Standards Update 2015-17 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred income taxes, current assets		$ (27,000,000)
Deferred income taxes, non-current liabilities		$ 27,000,000
[1]	Note: The condensed consolidated balance sheet at December 31, 2015 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Goodwill and Other Intangible29

Goodwill and Other Intangible Assets (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015		Sep. 27, 2013
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Goodwill	$ 307,365,845		$ 307,365,845		$ 307,365,845	[1]
Amortization expense, 2016	22,000,000		22,000,000
Amortization expense, 2017	22,000,000		22,000,000
Amortization expense, 2018	22,000,000		22,000,000
Amortization expense, 2019	22,000,000		22,000,000
Amortization expense, 2020	22,000,000		22,000,000
HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Goodwill							$ 307,400,000
Accumulated amortization	57,900,000		57,900,000		43,425,000
Gentex Patents
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Accumulated amortization	15,791,045		15,791,045		13,890,202
Patents and Other Intangible Assets
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Accumulated amortization	73,691,045		73,691,045		$ 57,315,202
Patents and Other Intangible Assets | HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Amortization expense	$ 5,600,000	$ 5,500,000	$ 16,700,000	$ 16,500,000
[1]	Note: The condensed consolidated balance sheet at December 31, 2015 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 ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 313,100,000	$ 327,575,000	[1]
Gentex Patents
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	32,302,452	31,873,665
Finite-lived intangible assets, accumulated amortization	(15,791,045)	(13,890,202)
Finite-lived intangible assets, net	16,511,407	17,983,463
Patents and Other Intangible Assets
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	(73,691,045)	(57,315,202)
Intangible assets, gross	403,302,452	402,873,665
Intangible assets, net	329,611,407	345,558,463
HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	(57,900,000)	(43,425,000)
Intangible assets, gross	371,000,000	371,000,000
Intangible assets, net	313,100,000	327,575,000
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	(45,000,000)	(33,750,000)
Finite-lived intangible assets, net	$ 135,000,000	$ 146,250,000
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	(12,900,000)	(9,675,000)
Finite-lived intangible assets, net	$ 30,100,000	$ 33,325,000
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, 2015 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Investments (Schedule of Amorti

Investments (Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value of Investment Securities) (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	$ 534,518,281	$ 551,557,527
Cost	205,008,466	98,427,114
Unrealized Gains	5,433,063	6,146,311
Unrealized Losses	(747,262)	(4,869,531)
Market Value	209,694,267	99,703,894
Investments and Cash	744,212,548	651,261,421
Short-term Investments [Member] | Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	130,000,000
Unrealized Gains	0
Unrealized Losses	0
Market Value	130,000,000
Short-term Investments [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	10,011,046	3,013,482
Unrealized Gains	1,799	0
Unrealized Losses	(2,235)	(2,622)
Market Value	10,010,610	3,010,860
Short-term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	6,773,386	1,512,405
Unrealized Gains	0	0
Unrealized Losses	(7,972)	(390)
Market Value	6,765,414	1,512,015	$ 6,765,414
Short-term Investments [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	125,217	24,480
Unrealized Gains	0	0
Unrealized Losses	0	0
Market Value	125,217	24,480
Short-term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	5,235,438
Unrealized Gains	99,140
Unrealized Losses	(66)
Market Value	5,334,512
Long-Term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	1,970,096
Unrealized Gains	0
Unrealized Losses	(2,002)
Market Value	1,968,094
Long-Term Investments [Member] | Common Stocks [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	10,978,179	17,395,641
Unrealized Gains	3,111,060	4,078,912
Unrealized Losses	(395,605)	(1,019,749)
Market Value	13,693,634	20,454,804
Long-Term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	39,536,844	76,481,106
Unrealized Gains	2,206,543	2,067,399
Unrealized Losses	(339,382)	(3,846,770)
Market Value	41,404,005	74,701,735
Long-Term Investments [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	378,260
Unrealized Gains	14,521
Unrealized Losses	0
Market Value	392,781
Fair Value, Inputs, Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	534,518,281	551,557,527
Investments and Cash	720,133,918	646,738,546
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
Fair Value, Inputs, Level 1 [Member] | Short-term Investments [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	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	125,217	24,480
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] | 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	13,693,634	20,454,804
Fair Value, Inputs, Level 1 [Member] | Long-Term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	41,404,005	74,701,735
Fair Value, Inputs, Level 1 [Member] | Long-Term Investments [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	392,781
Fair Value, Inputs, Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	0	0
Investments and Cash	24,078,630	4,522,875
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
Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	10,010,610	3,010,860
Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value		1,512,015	6,765,414
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] | Short-term Investments [Member] | Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	5,334,512
Fair Value, Inputs, Level 2 [Member] | Long-Term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	1,968,094
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 [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	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
Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member] | US Government Agencies Debt Securities [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] | Short-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
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 [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	$ 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

Investments (Schedule of Unreal

Investments (Schedule of Unrealized Loss on Investments) (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Investments [Abstract]
Aggregate Unrealized Losses, Less than one year	$ 506,734	$ 4,869,531
Aggregate Fair Value, Less than one year	31,401,343	65,440,181
Aggregate Unrealized Losses, Greater than one year	240,528	0
Aggregate Fair Value, Greater than one year	1,481,420	0
Aggregate Unrealized Losses, Total	747,262	4,869,531
Aggregate Fair Value, Total	32,882,763	65,440,181
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]	Sep. 30, 2016USD ($)
Schedule of Available-for-sale Securities [Line Items]
Due within one year	$ 146,776,024
Due between one and five years	1,968,094
Due over five years	0
Total	$ 148,744,118

Inventories (Schedule of Invent

Inventories (Schedule of Inventories) (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 108,033,204	$ 110,683,958
Work-in-process	31,230,322	27,077,220
Finished goods	40,090,077	36,934,233
Total Inventory	$ 179,353,603	$ 174,695,411	[1]
[1]	Note: The condensed consolidated balance sheet at December 31, 2015 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Earnings Per Share (Schedule of

Earnings Per Share (Schedule of Earnings Per Share, Basic And Diluted) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerators [Abstract]
Numerator for both basic and diluted EPS, net income	$ 92,064,646	$ 78,332,425	$ 258,829,882	$ 230,074,303
Denominators [Abstract]
Denominator for basic EPS, weighted-average shares outstanding	287,736,638	292,589,866	288,466,905	293,742,028
Potentially dilutive shares resulting from stock plans	2,717,187	2,787,612	2,557,758	3,252,544
Denominator for diluted EPS	290,453,825	295,377,478	291,024,663	296,994,572
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive	1,818,032	3,756,396	4,193,947	1,611,900

Stock-Based Compensation Plan36

Stock-Based Compensation Plans (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)planshares	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)planshares	Sep. 30, 2015USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense for share-based payments | $	$ 3,724,780	$ 4,404,297	$ 11,558,462	$ 13,979,297
Compensation cost capitalized as part of inventory | $			$ 317,315	$ 279,903
Employee Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (in shares) | shares	24,000,000		24,000,000
Unrecognized compensation cost | $	$ 18,589,743		$ 18,589,743
Employee Stock Option Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			1 year
Option expiration period			5 years
Employee Stock Option Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			5 years
Option expiration period			7 years
Non-Employee Director Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			6 months
Option expiration period			10 years
Number of shares authorized (in shares) | shares	1,000,000		1,000,000
Unrecognized compensation cost | $	$ 66,324		$ 66,324
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		2,000,000
ESPP discount rate			85.00%
Shares granted (in shares) | shares	585,668		585,668
ESPP discount rate recognized as compensation expense			15.00%
Restricted Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares) | shares	9,000,000		9,000,000
Restricted period, maximum, in years			10 years
Unearned stock-based compensation | $	$ 11,816,334		$ 11,816,334
Amortization expense | $	$ 1,001,100		$ 2,944,845
Equity Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans (in plans) | plan	4		4
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans (in plans) | plan	2		2

Stock-Based Compensation Plan37

Stock-Based Compensation Plans (Weighted-Average Assumptions for the ESOP) (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Dividend yield	2.19%	2.12%	2.17%	2.13%
Expected volatility	32.19%	35.81%	33.62%	36.10%
Risk-free interest rate	1.14%	1.37%	1.18%	1.56%
Expected term of options	4 years 105 days	4 years 3 months 22 days	4 years 94 days	4 years 11 months 19 days
Weighted-avg. grant-date fair value (in dollars per share)	$ 3.91	$ 3.94	$ 3.74	$ 4.47

Comprehensive Income (AOCI Roll

Comprehensive Income (AOCI Rollforward) (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[1]			$ (1,130,836)
Comprehensive Income		$ 95,097,463	$ 69,430,897	259,517,937	$ 216,999,662
Balance at end of period		(442,780)	(1,761,626)	(442,780)	(1,761,626)
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(1,473,888)	761,692	(44,909)	1,403,899
Other Comprehensive (loss) income before reclassifications		162,343	(396,685)	(1,266,636)	(1,038,892)
Comprehensive Income		162,343	(396,685)	(1,266,636)	(1,038,892)
Balance at end of period		(1,311,545)	365,007	(1,311,545)	365,007
Unrealized gains on available-for-sale securities:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		870,945	8,551,564	829,907	10,868,322
Other Comprehensive (loss) income before reclassifications		2,269,315	(6,353,685)	1,993,505	(5,727,233)
Amounts reclassified from accumulated other comprehensive income		(94,489)	(1,321,982)	222,359	(4,265,192)
Comprehensive Income		2,174,826	(7,675,667)	2,215,864	(9,992,425)
Balance at end of period		3,045,771	875,897	3,045,771	875,897
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(2,872,655)	(2,173,354)	(1,915,834)	(959,206)
Other Comprehensive (loss) income before reclassifications		353,397	(1,113,648)	(1,321,890)	(2,327,796)
Amounts reclassified from accumulated other comprehensive income		342,252	284,472	1,060,718	284,472
Comprehensive Income		695,649	(829,176)	(261,172)	(2,043,324)
Balance at end of period		$ (2,177,006)	$ (3,002,530)	$ (2,177,006)	$ (3,002,530)
[1]	Note: The condensed consolidated balance sheet at December 31, 2015 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Comprehensive Income (Reclassif

Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	$ (42,263,336)	$ (37,715,317)	$ (122,676,422)	$ (104,841,502)
Amounts Reclassified from Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period	(247,763)	1,037,510	(1,283,077)	3,980,720
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	145,367	2,033,819	(342,090)	6,561,834
Provision for Income Taxes	(50,878)	(711,837)	119,732	(2,296,642)
Total reclassifications for the period	94,489	1,321,982	(222,358)	4,265,192
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	(526,542)	(437,650)	(1,631,875)	(437,650)
Provision for Income Taxes	184,290	153,178	571,156	153,178
Total reclassifications for the period	$ (342,252)	$ (284,472)	$ (1,060,719)	$ (284,472)

Debt and Financing Arrangemen40

Debt and Financing Arrangements (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015		Oct. 01, 2014	Sep. 27, 2013
Debt Instrument [Line Items]
Long-term debt	$ 195,000,000			$ 195,000,000		$ 225,625,000	[1]
Financial Liabilities:
Effect of 1% in increase on borrowing rate	500,000			500,000
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Amount of hedged item								$ 150,000,000
Notional amount of derivative	150,000,000			150,000,000		150,000,000		$ 150,000,000
Fixed interest rate of derivative								1.89%
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Interest Rate Swap Asset	0			0		0
Financial Liabilities:
Interest Rate Swap Liability (Other Accrued Liabilities)	3,349,240			3,349,240		$ 2,947,438
Other, Net [Member]
Debt Instrument [Line Items]
Payments of financing costs	800,000		$ 800,000	2,500,000	$ 2,400,000
Other, Net [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Interest expense	500,000		$ 500,000	$ 1,600,000	$ 500,000
LIBOR Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate				1.53%
Term Loan and Revolving Facility [Member]
Debt Instrument [Line Items]
Partial repayment of debt	11,800,000			$ 30,600,000
Revolving Facility [Member]
Debt Instrument [Line Items]
Partial repayment of debt	10,000,000	$ 15,000,000
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	75,700,000			75,700,000
Available borrowing capacity	74,300,000			74,300,000
Term Loan [Member]
Debt Instrument [Line Items]
Principal amount									150,000,000
Long-term debt	127,500,000			127,500,000
Annual principal repayments	$ 7,500,000			$ 7,500,000
Swing Loans [Member]
Debt Instrument [Line Items]
Additional principal amount available									20,000,000
Letters of Credit [Member]
Debt Instrument [Line Items]
Additional principal amount available									$ 20,000,000
[1]	Note: The condensed consolidated balance sheet at December 31, 2015 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				9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Equity [Abstract]
Stock repurchased (in shares)					8,041,358
Common stock issued under stock compensation plan (in shares)					4,632,945
Net decrease in period (in shares)					3,408,413
Increase in quarterly cash dividend rate (in dollars per share)	$ 0.005
Dividends declared (in dollars per share)	$ 0.09	$ 0.09	$ 0.085	$ 0.085	$ 0.265	$ 0.25
Dividends declared	$ 25.9

Segment Reporting (Schedule Of

Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenue	$ 429,643,276	$ 389,829,139	$ 1,259,011,840	$ 1,138,025,071
Income from operations	134,212,281	116,262,620	383,806,992	332,103,956
Automotive Products
Segment Reporting Information [Line Items]
Revenue	419,793,577	379,889,957	1,228,165,639	1,111,009,546
Income from operations	130,567,201	112,238,938	372,119,627	322,289,461
Other
Segment Reporting Information [Line Items]
Revenue	9,849,699	9,939,182	30,846,201	27,015,525
Income from operations	$ 3,645,080	$ 4,023,682	$ 11,687,365	$ 9,814,495

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Effective income tax rate	32.20%	31.30%
Reversal of uncertain tax position related to incremental research and development tax credits	$ 3.9