Gentex (GNTX) 10-Q 12 Nov 13 2013 Q3 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 23, 2013
Document And Entity Information [Abstract]	'	'
Entity Registrant Name	'GENTEX CORPORATION	'
Entity Central Index Key	'0000355811	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Amendment Flag	'false	'
Trading Symbol	'gntx	'
Entity Common Stock, Shares Outstanding	'	144,730,834

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2013		Dec. 31, 2012
CURRENT ASSETS	'		'
Cash and cash equivalents	$226,676,955		$389,678,664
Short-term investments	0		60,802,856
Accounts receivable, net	152,437,232		109,579,693
Inventories	117,406,559		159,930,266
Prepaid expenses and other	27,330,903		24,671,561
Total current assets	523,851,649		744,663,040
PLANT AND EQUIPMENT—NET	351,066,630		349,938,172
OTHER ASSETS	'		'
Goodwill	337,670,463		0
Long-term investments	114,270,623		141,834,034
Patents and other assets, net	370,268,798		29,256,089
Total other assets	822,209,884		171,090,123
Total assets	1,697,128,163		1,265,691,335
CURRENT LIABILITIES	'		'
Accounts payable	50,339,389		43,200,002
Accrued liabilities	70,251,042		44,757,440
Total current liabilities	120,590,431		87,957,442
LONG TERM DEBT	267,500,000		0
DEFERRED INCOME TAXES	53,730,295		56,773,337
TOTAL LIABILITIES	441,820,726		144,730,779
SHAREHOLDERS’ INVESTMENT	'		'
Common stock	8,683,729		8,584,581
Additional paid-in capital	455,997,100		418,766,010
Retained earnings	768,527,760		676,039,254
Accumulated other comprehensive income	22,098,848	[1]	17,570,711
Total shareholders’ investment	1,255,307,437		1,120,960,556
Total liabilities and shareholders’ investment	$1,697,128,163		$1,265,691,335
[1]	All amounts are shown net of tax. Amounts in parentheses indicate debits.

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Income (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]	'	'	'	'
NET SALES	$288,621,626	$268,248,089	$845,094,493	$839,210,399
COST OF GOODS SOLD	182,659,141	178,132,021	543,055,886	555,510,532
Gross profit	105,962,485	90,116,068	302,038,607	283,699,867
OPERATING EXPENSES:	'	'	'	'
Engineering, research and development	19,106,682	20,434,012	56,654,440	66,441,649
Selling, general & administrative	13,199,557	12,058,701	36,278,011	36,621,668
Total operating expenses	32,306,239	32,492,713	92,932,451	103,063,317
Income from operations	73,656,246	57,623,355	209,106,156	180,636,550
OTHER INCOME	'	'	'	'
Investment income	474,084	586,517	1,595,214	1,816,240
Other, net	6,912,924	3,476,189	13,224,735	8,700,309
Total other income	7,387,008	4,062,706	14,819,949	10,516,549
Income before provision for income taxes	81,043,254	61,686,061	223,926,105	191,153,099
PROVISION FOR INCOME TAXES	25,522,293	19,808,978	70,877,180	62,164,893
NET INCOME	$55,520,961	$41,877,083	$153,048,925	$128,988,206
EARNINGS PER SHARE:	'	'	'	'
Basic (in dollars per share)	$0.39	$0.29	$1.07	$0.90
Diluted (in dollars per share)	$0.38	$0.29	$1.06	$0.89
Cash Dividends Declared per Share (in dollars per share)	$0.14	$0.13	$0.42	$0.39

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Other Comprehensive Income [Abstract]	'	'	'	'
Net income	$55,520,961	$41,877,083	$153,048,925	$128,988,206
Other comprehensive income (loss) before tax:	'	'	'	'
Foreign currency translation adjustments	273,097	275,648	-99,537	-164,559
Unrealized gains on available-for sales securities, net	1,598,977	4,198,182	7,119,498	8,829,548
Other comprehensive income, before tax	1,872,074	4,473,830	7,019,961	8,664,989
Provision for income taxes related to components of other comprehensive income	559,642	1,469,364	2,491,824	3,090,342
Other comprehensive income, net of tax	1,312,432	3,004,466	4,528,137	5,574,647
Comprehensive Income	$56,833,393	$44,881,549	$157,577,062	$134,562,853

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:	'	'
Net income	$153,048,925	$128,988,206
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	42,334,977	37,620,512
Loss on disposal of assets	2,114,241	327,382
Gain on sale of investments	-15,121,583	-8,420,229
Loss on sale of investments	805,805	841,274
Deferred income taxes	-6,271,382	2,923,004
Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock	12,528,264	12,361,993
Excess tax benefits from stock-based compensation	-2,275,233	-641,072
Change in operating assets and liabilities:	'	'
Accounts receivable, net	-31,755,237	-15,882,832
Inventories	42,523,707	11,633,857
Prepaid expenses and other	-12,362	4,403,912
Accounts payable	7,139,387	-13,236,250
Accrued liabilities, excluding dividends declared	18,606,444	15,529,686
Net cash provided by operating activities	223,665,953	176,449,443
Activity in available-for-sale securities:	'	'
Sales proceeds	69,937,242	31,564,139
Maturities and calls	98,142,408	70,652,000
Purchases	-58,278,107	-63,441,410
Plant and equipment additions	-38,026,769	-97,597,283
Proceeds from sale of plant and equipment	316,449	1,012,608
Acquisition of businesses, net of cash acquired	-698,107,014	0
(Increase) decrease in other assets	-602,017	-16,036,911
Net cash (used for) provided by investing activities	-626,617,808	-73,846,857
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'
Proceeds from borrowings on Credit Agreement	275,000,000	0
Financing costs paid	-953,800	0
Issuance of common stock from stock plan transactions	22,526,742	8,417,982
Cash dividends paid	-58,898,029	-54,829,734
Repurchases of common stock	0	-33,716,725
Excess tax benefits from stock-based compensation	2,275,233	641,072
Net cash provided by (used for) financing activities	239,950,146	-79,487,405
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	-163,001,709	23,115,181
CASH AND CASH EQUIVALENTS, beginning of period	389,678,664	357,986,774
CASH AND CASH EQUIVALENTS, end of period	$226,676,955	$381,101,955

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2013
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 Registrant, 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 Registrant 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 Registrant’s 2012 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 Registrant as of September 30, 2013, and the results of operations and cash flows for the interim periods presented.

Business_Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Business Combinations	'
	Business Combinations
	On September 27, 2013, the Company completed its previously announced acquisition of certain assets and liabilities of Johnson Controls, Inc. (the “Seller”) related to the Seller’s wireless vehicle/home communication HomeLink® business (the “Business”). Prior to the above-described acquisition, the Seller supplied HomeLink products and was a licensor of HomeLink to the Company, which allowed for incorporation into the Company’s rearview mirror products, that are installed in automobiles. The aggregate purchase price for the Business (the “Purchase Price”) paid at the closing was approximately $700 million, subject to adjustments as provided in the Asset Purchase Agreement, by and between the Company and the Seller, dated July 18, 2013.
	The HomeLink acquisition was done to secure the Company’s current customers and product offerings in HomeLink mirrors and to enable and expand its capabilities beyond the mirror. Even prior to the acquisition the Company offered HomeLink mirrors as part of its existing product portfolio. HomeLink mirror products have been sold by the Company in the marketplace for over 10 years, where the Company was previously a licensee of the technology. After the acquisition, there are certain synergies the Company hopes to capitalize upon. There is significant value in the HomeLink brand, including consumer awareness when shopping for new automobiles equipped with the feature. The acquisition enables the Company to continue its long history of development and growth of the Homelink mirror based products, as well as to add HomeLink products that are not based in the mirror. The Company believes it will be able to apply its expertise in electronics manufacturing to enhance even further the quality and reliability of the HomeLink products.
	The assets acquired and liabilities assumed were recorded at fair value on the acquisition date. The Company accounted for the acquisition under the provisions of FASB ASC Topic 805, Business Combinations. There were no revenues or earnings, related to the Business, for the quarter and year to date period ended September 30, 2013, included in the the Company’s consolidated statement of income and comprehensive income. The operating results for the Business will be included in Automotive Products segment in future periods, consistent with the Company's treatment of other features.
	Separate from the Asset Purchase Agreement, the Seller and the Company have entered into a Supply Agreement, in the ordinary course of business, whereby the Company agrees to supply HomeLink product to the Seller for incorporation into the Seller’s vehicular products. The Supply Agreement contains customary terms and conditions which are consistent with market rates for sales of similar products to other parties. Due to the nature of the Supply Agreement and the fact that terms are at arms length, there has not been a portion of the purchase price which has been allocated to the Supply Agreement.
	The Company funded the transaction using a combination of cash on hand of approximately $423 million and debt financing. The Company’s debt financing included net proceeds from the Company’s new Credit Agreement as described in Footnote 10.
	Through September 30, 2013, the Company has incurred acquisition-related costs of approximately $3,121,000 of which approximately $2,167,000 has been expensed as incurred in the "Selling, general & administrative" section of its Condensed Consolidated Income Statement. The remaining costs of approximately $954,000, were related to the issuance of the Company's new debt financing, further explained in Note 10, which has been classified in the "Prepaid Expenses and Other" section of its' Condensed Consolidated Balance Sheet and will be amortized over the life of the credit agreement.
	The preliminary allocation of the purchase price through September 30, 2013 is as follows:
	Net Assets Acquired	Fair Value
	Prepaid Service Agreement Costs	$	3,383,000
	Personal Property	4,430,986
	Real Property	1,060,000
	HomeLink Trade Names and Trademarks	47,000,000
	Homelink Technology	166,000,000
	Existing Customer Platforms	43,000,000
	Exclusive Licensing Agreement	87,000,000
	Accounts Receivable	7,719,302
	Net Customer Tooling	956,665
	Fair Value of Acquired Assets	360,549,953
	Goodwill	337,557,061
	Total Cash Consideration	$	698,107,014
	Management preliminarily assigned fair values to the identifiable intangible assets through a combination of the relief from royalty and the excess earnings methods.The allocation of the purchase price above is considered preliminary and was based upon valuation information available and estimates and assumptions made as of September 30, 2013. The Company is still in the process of verifying data and finalizing information related to the valuation and recording of identifiable intangible assets, net working capital,and the resulting effects on the amount of recorded goodwill. The Company expects to finalize these matters within the measurement period, which is currently expected to remain open through the first quarter of calendar 2014.
	The following unaudited pro forma condensed consolidated statement of income for nine month periods ended September 30, 2013 and 2012 include pro-forma adjustments to reflect the effect of the acquisition as if it had occurred on January 1, 2013. This unaudited pro forma consolidated statement of income is provided for informational purposes only and does not purport to be indicative of the results which would have actually been attained had the acquisition occurred on January 1, 2013 or that may be attained in the future.
	PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF INCOME
	Nine Months Ended September 30,
		2013		2012
	Net Sales	$	944,550	$	931,221
	Net Income	187,250		159,781

Adoption_of_New_Accounting_Sta

Adoption of New Accounting Standards	9 Months Ended
	Sep. 30, 2013
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]	'
Adoption of New Accounting Standards	'
	Adoption of New Accounting Standards
	In February 2013, FASB issued Accounting Standards Update No. 2013-02, “Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income” (“ASU 2013-12”).  ASU 2013-02 requires an entity to report the effect of significant reclassifications out of accumulated other comprehensive income.  The amended guidance does not change the current requirements for reporting net income or other comprehensive income in financial statements.  However, the amended guidance requires an entity to provide information regarding the amounts reclassified out of accumulated other comprehensive income by component, either on the face of the statement where net income is presented or in the notes to the condensed consolidated financial statements.  The amended guidance was effective for financial periods beginning after December 15, 2012.  ASU 2013-02 did not have a material effect on the Company's consolidated financial position or results of operations.

Goodwill_and_Other_Intangible_

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2013
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 $337.6 million, which is based on preliminary valuations of tangible and intangible assets acquired as part of the HomeLink acquisition. The amount of Goodwill that is expected to be deductible for tax purposes is $337.6 million.
	The Intangible assets as of September 30, 2013 consist of the following:
	Other Intangible Assets	Gross		Accumulated Amortization		Net		Assumed Useful Life
	HomeLink Trade Names and Trademarks	$	47,000,000	—		$	47,000,000	Indefinite
	HomeLink Technology	166,000,000		—		166,000,000		10 to 15 years
	Existing Customer Platforms	43,000,000		—		43,000,000		10 years
	Exclusive Licensing Agreement	87,000,000		—		87,000,000		Indefinite
	Total other identifiable intangible assets	$	343,000,000	$	—	$	343,000,000
	The Homelink Trade Name and Trademarks were valued utilizing the relief from royalty valuation method, which is a function of projected revenue, the royalty rate that would hypothetically be charged by a licensor of an asset to an unrelated licensee discounted utilizing market participants weighted average cost of capital. The royalty rate utilized in the analysis was a combination of the historical royalty rate that was paid by the Company to the Seller for the right to use the HomeLink name in the market and the manufacturing of products using HomeLink's propietary technology, as well as other market transactions within the industry. Further, the royalty rate made considerations for factors such as age, market competition, absolute and relative profitability, market share and prevailing rates from similar assets. The discount rate applied was based on the weighted average cost of capital.
	The HomeLink Technology and the Existing Customer Platform assets were valued using forms of the multi-period excess earnings valuation method which estimates future revenues and cash flows derived from the technology, and then subsequently deducts portions of future cash flow that is supported by other intangibles and fixed assets. The resulting cash flows are discounted using a weighted average cost of capital.
	The Exclusive Licensing Agreement asset was valued based on a "with or without" methodology. This method compares the Company's estimated future cash flow projections with the exclusive agreement compared to those same cash flows without that exclusive license agreement.
	As the valuation methodologies for the aforementioned intangible assets utilize unobservable inputs, the Company considers the estimated fair value of the assets to be a level 3 measurement in the fair value hierarchy.
	There was no amortization expense related to the above identified intangible assets during the three or nine month periods ended September 30, 2013, due to the timing of the closing of the acquisition.
	Amortization expense for the year ended December 31, 2013, including existing and newly acquired intangible assets as part of the HomeLink acquisition, is estimated to be approximately $7.6 million. Amortization expense for each of the years ended December 31, 2014, 2015, 2016, 2017 and 2018 is estimated to be approximately $20.8 million per year, based on the preliminary purchase price allocation.

Investments

Investments	9 Months Ended
	Sep. 30, 2013
Investments [Abstract]	'
Investments	'
	Investments
	The Company follows the provisions of ASC 820, “Fair Value Measurements and Disclosures” for its financial assets and liabilities, and to 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 determines the fair value of its U.S. Treasury Notes, Government Securities and Corporate Bonds by utilizing monthly valuation statements that are provided by its broker, and the Company utilizes third party pricing sources to validate such statements. The broker determines the investment valuation by utilizing the bid price in the market. As such, these investments are classified as Level 2 assets.
	Assets or liabilities that have recurring measurements are shown below as of September 30, 2013, and December 31, 2012:
				Fair Value Measurements at Reporting Date Using
		Total as of		Quoted Prices in		Significant			Significant
				Active Markets for		Other			Unobservable
				Identical Assets		Observable			Inputs
						Inputs
	Description	30-Sep-13		(Level 1)		(Level 2)			(Level 3)
	Cash & Cash Equivalents	$	226,676,955	$	226,676,955				$	—
	Long-Term Investments:
	Common Stocks	37,646,607		37,646,607		—			—
	Mutual Funds – Equity	76,624,016		76,624,016		—			—
	Total	$	340,947,578	$	340,947,578	$	—		$	—
				Fair Value Measurements at Reporting Date Using
		Total as of		Quoted Prices in		Significant Other			Significant
				Active Markets for		Observable			Unobservable
				Identical Assets		Inputs			Inputs
	Description	31-Dec-12		(Level 1)		(Level 2)			(Level 3)
	Cash & Cash Equivalents	$	389,678,664	$	389,678,664	$	—		$	—
	Short-Term Investments:
	Certificate of Deposit	510,881		—		510,881			—
	Government Securities	38,522,471		—		38,522,471			—
	U.S. Treasury Notes	15,020,350		—		15,020,350			—
	Corporate Bonds	6,563,228		—		6,563,228			—
	Other	185,926		185,926		—			—
	Long-Term Investments:
	Corporate Bonds	2,180,780		—		2,180,780			—
	Common Stocks	53,283,201		53,283,201		—			—
	Mutual Funds – Equity	86,109,053		86,109,053		—			—
	Other – Equity	261,000		261,000		—			—
	Total	$	592,315,554	$	529,517,844	$	62,797,710		$	—
	The amortized cost, unrealized gains and losses, and market value of investment securities are shown as of September 30, 2013, and December 31, 2012:
	As of September 30, 2013:
				Unrealized
		Cost		Gains		Losses			Market Value
	Long-Term Investments:
	Common Stocks	$	27,830,723	$	9,962,493	$	(146,609	)	$	37,646,607
	Mutual Funds – Equity	56,071,512		20,552,504		—			76,624,016
	Total	$	83,902,235	$	30,514,997	$	(146,609	)	$	114,270,623
	As of December 31, 2012:
				Unrealized
		Cost		Gains		Losses			Market Value
	Short-Term Investments:
	Certificate of Deposit	$	510,881	$	—	$	—		$	510,881
	Government Securities	38,514,411		9,004		(944		)	38,522,471
	U.S. Treasury Notes	15,018,810		2,602		(1,062		)	15,020,350
	Corporate Bonds	6,529,758		33,470		—			6,563,228
	Other	185,926		—		—			185,926
	Long-Term Investments:
	Corporate Bonds	2,174,948		5,832		—			2,180,780
	Common Stocks	40,893,121		12,781,501		(391,421		)	53,283,201
	Mutual Funds – Equity	75,321,640		11,082,714		(295,301		)	86,109,053
	Other – Equity	238,506		22,494		—			261,000
	Total	$	179,388,001	$	23,937,617	$	(688,728	)	$	202,636,890
	Unrealized losses on investments as of September 30, 2013, are as follows:
		Aggregate Unrealized Losses		Aggregate Fair Value
	Less than one year	$	146,609	$	37,646,607
	Unrealized losses on investments as of December 31, 2012, are as follows:
		Aggregate Unrealized Losses		Aggregate Fair Value
	Less than one year	$	688,728	$	22,887,686
	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 fixed income and 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 at September 30, 2013.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2013
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories consisted of the following at the respective balance sheet dates:
		September 30, 2013		31-Dec-12
	Raw materials	$	72,278,273	$	114,750,525
	Work-in-process	23,466,112		24,588,734
	Finished goods	21,662,174		20,591,007
	Total Inventory	$	117,406,559	$	159,930,266

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2013
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,
		2013		2012		2013		2012
	Numerators:
	Numerator for both basic and diluted EPS, net income	$	55,520,961	$	41,877,083	$	153,048,925	$	128,988,206
	Denominators:
	Denominator for basic EPS, weighted-average shares outstanding	143,697,760		143,027,693		143,160,402		143,415,077
	Potentially dilutive shares resulting from stock plans	821,140		556,682		655,639		1,002,142
	Denominator for diluted EPS	144,518,900		143,584,375		143,816,041		144,417,219
	Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive	3,220,980		5,332,661		3,573,418		3,289,832

StockBased_Compensation_Plans

Stock-Based Compensation Plans	9 Months Ended
	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock-Based Compensation Plans	'
	Stock-Based Compensation Plans
	At September 30, 2013, the Company had four equity incentive plans which include two stock option plans, a restricted stock plan and an employee stock purchase plan, each of which has 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, 2012, for additional information related to these stock-based compensation plans.
	The Company recognized compensation expense for share-based payments of $3,795,626 and $10,529,514 for the third quarter and nine months ended September 30, 2013, respectively. Compensation cost capitalized as part of inventory as of September 30, 2013, was $203,872.
	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				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
	Dividend Yield (1)	2.64	%	2.67	%	2.7	%	2.64	%
	Expected volatility (2)	44.9	%	46.91	%	45.61	%	45.17	%
	Risk-free interest rate (3)	1.39	%	0.64	%	1.19	%	0.79	%
	Expected term of options (years) (4)	4		4.05		4.01		4.04
	Weighted-avg. grant date fair value	$7.61		$5.23		$6.98		$6.09
	(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 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 two to seven years.
	As of September 30, 2013, there was $23,234,157 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
	As of September 30, 2013, there was $96,540 of unrecognized compensation cost under the plan related to share-based payments. The Company has granted options on 84,000 shares under the director plan through September 30, 2013. Under the 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
	In May 2013, the 2013 Gentex Corporation Employee Stock Purchase Plan covering 1,000,000 shares of common stock, was approved by shareholders replacing a prior plan. Under the plan, the Company sells shares at 85% of the stock’s market price at date of purchase. Under ASC 718, the 15% discounted value is recognized as compensation expense.
	Restricted Stock Plan
	The Company has a restricted stock plan covering 2,000,000 shares of common stock. The purpose of the plan is to permit grants of shares, subject to restrictions, to key employees of the Company as a means of retaining and rewarding them for long-term performance and to increase their ownership in the Company. Shares awarded under the 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, 2013, the Company had unearned stock-based compensation of $9,867,574 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 and nine months ended September 30, 2013 was $654,683 and $1,998,750, respectively.

Comprehensive_Income

Comprehensive Income	9 Months Ended
	Sep. 30, 2013
Comprehensive Income [Abstract]	'
Comprehensive Income	'
	Comprehensive Income
	Comprehensive income reflects the change in equity of a business enterprise during a period from
	transactions and other events and circumstances from non-owner sources. For the Company,
	comprehensive income represents net income adjusted for unrealized gains and losses on certain
	investments and foreign currency translation adjustments.
	The following table presents the net changes in the Company's accumulated other comprehensive income by component (1):
		For Three Months Ended September 30,								For Nine Months Ended September 30,
		2013				2012				2013				2012
	Foreign currency translation adjustments:
	Balance at beginning of period	$	2,086,299			$	1,689,750			$	2,458,933			$	2,129,957
	Other Comprehensive income before reclassifications	273,097				275,648				(99,537		)		(164,559		)
	Amounts reclassified from accumulated other comprehensive income	—				—				—				—
	Net current-period change	273,097				275,648				(99,537		)		(164,559		)
	Balance at end of period	2,359,396				1,965,398				2,359,396				1,965,398
	Unrealized gains(losses) on available-for-sale securities:
	Balance at beginning of period	18,700,117				13,422,635				15,111,778				10,412,246
	Other Comprehensive income before reclassifications	5,240,576				4,901,805				13,932,930				10,665,529
	Amounts reclassified from accumulated other comprehensive income	(4,201,241		)		(2,172,986		)		(9,305,256		)		(4,926,321		)
	Net current-period change	1,039,335				2,728,819				4,627,674				5,739,208
	Balance at end of period	19,739,452				16,151,454				19,739,452				16,151,454
	Accumulated other comprehensive income, end of period	$	22,098,848			$	18,116,852			$	22,098,848			$	18,116,852
	(1) All amounts are shown net of tax. Amounts in parentheses indicate debits.
	The following table presents details of reclassifications out of other comprehensive income for the three and nine months ended September 30, 2013 and 2012.
	Details about Accumulated Other Comprehensive Income Components (2)		Amounts Reclassified from Other Comprehensive Income															Affected Line item in the Statement of Consolidated Income
			For the Three Months ended September 30,								For the Nine Months ended September 30,
			2013				2012				2013				2012
	Unrealized gains and (losses) on available-for-sale securities
	Realized gain (loss) on sale of securities		$	6,463,447			$	3,343,055			$	14,315,778			$	7,578,955		Other, net
	Provision for Income Taxes		(2,262,206		)		(1,170,069		)		(5,010,522		)		(2,652,634		)	Provision for Income Taxes
	Total reclassifications for the period		$	4,201,241			$	2,172,986			$	9,305,256			$	4,926,321		Net of tax
	(2) Amounts in parentheses indicate debits.

Debt_and_Financing_Arrangement

Debt and Financing Arrangements	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Debt and Financing Arrangements	'
	Debt and Financing Arrangements
	On September 27, 2013, the Company entered into a Credit Agreement (the “Credit Agreement”) with certain banks and agents.
	Pursuant to the Credit Agreement, the Company is borrower under a $150,000,000 senior revolving credit facility (the “Revolving Facility”) and a $150,000,000 term loan facility (the “Term Loan”). Under the terms of the Credit Agreement, the Company is entitled, subject to the satisfaction of certain conditions, to further request an additional aggregate principal amount of up to $75,000,000. In addition, the Company is entitled, subject to certain terms and conditions, to the benefit of swing loans from amounts otherwise available under the Revolving Facility in the aggregate principal amount of up to $20,000,000 and to request Letters of Credit from amounts otherwise available under the Revolving Facility in the aggregate principal amount of up to $20,000,000. The obligations of the Company under the Credit agreement are not secured, but are subject to certain covenants (see below).
	The interest rates per annum applicable to loans, other than swing loans, under the Credit Agreement will be, at the Company’s option and subject to certain conditions, equal to either a base rate or a LIBOR rate for one, two, three or six-month interest periods chosen by the Company, plus an applicable margin percentage. The base rate will be the highest of (i) the federal funds rate plus 0.50%, (ii) the agent’s prime rate or (iii) the LIBOR rate plus 1.00%. The LIBOR rate will be equal to the London interbank offered rates for U.S. Dollars quoted by Bloomberg or the appropriate successor, divided by a number equal to 1 minus the maximum percentage in effect on such day for determining reserve requirements, as prescribed by the Board of Governors of the Federal Reserve System. The applicable margin percentage is based on the leverage ratio of the Company. The range of the applicable margin percentage is 1.00% per annum to 1.75% per annum in the case of the LIBOR rate and 0.00% per annum to 0.75% per annum in the case of the base rate.
	As of September 30, 2013, the Company is borrowing funds using the one month LIBOR option, and based on the Company's leverage ratio as of September 30, 2013, the interest rate on it's borrowings is equal to 1.18%.
	The Revolving Facility expires and the Term Loan matures on September 27, 2018.
	The Credit Agreement contains customary representations and warranties and certain covenants that limit the ability of the Company and certain of its subsidiaries to, among other things: (i) incur or guarantee additional indebtedness; (ii) redeem or repurchase subordinated debt; (iii) sell or otherwise transfer or dispose of certain assets; (iv) make certain investments; (v) incur or suffer to exists liens securing indebtedness; (vi) dissolve, liquidate, consolidate, merge or wind-up its affairs; (vii) engage in certain transactions with affiliates; or (viii) make certain other negative pledges. In addition, the Credit Agreement contains financial covenants that limit capital expenditures in any fiscal year and that measure (i) the ratio of the Company’s total funded indebtedness net of certain cash to the amount of the Company’s consolidated Earnings Before Interest, Taxes, Deprectiation and Amortization ("EBITDA") and (ii) the ratio of the amount of the Company’s consolidated EBITDA to the Company’s cash interest expense. The Credit Agreement also includes customary events of default.
	In connection with the business combination discussed more fully in Note 2, the Company borrowed $275 million related to the Credit Agreement, which was broken down further into $125 million under the revolving facility and $150 million on the term loan. As of September 30, 2013, the Company had availability of $25 million under the Credit Agreement (not including additional aggregate principal amounts which can be requested).
	As of September 30, 2013, the Company was in compliance with its covenants under the Credit Agreement.

Equity

Equity	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Equity	'
	Equity
	The increase in common stock during the nine months ended September 30, 2013, was primarily due to the issuance of 1,654,477 shares of the Company’s common stock under the Company’s stock-based compensation plans. The Company announced a $0.01 per share increase in its quarterly cash dividend rate during the first quarter of 2013, which resulted in a recorded cash dividend of $0.14 per share in the first, second and third quarters of 2013. The third quarter dividend of $20.3 million was declared on August 20, 2013, and was paid on October 18, 2013.

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2013
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, 2013
Segment Reporting [Abstract]	'
Segment Reporting	'
	Segment Reporting
	The Company develops and manufactures electro-optic products, including: automatic-dimming rearview mirrors with and without electronic features for the automotive industry; non-auto dimming rearview automotive mirrors with and without electronic features and HomeLink, the vehicle-based control system that enables drivers to remotely activate garage door openers, entry door locks, home lighting, security systems, entry gates, and other radio frequency convenience products. The Company also develops and manufactures variably dimmable 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,
		2013		2012		2013		2012
	Revenue:
	Automotive Products	$	280,924,112	$	261,910,519	$	823,681,484	$	822,415,871
	Other	7,697,514		6,337,570		21,413,009		16,794,528
	Total	$	288,621,626	$	268,248,089	$	845,094,493	$	839,210,399
	Income from operations:
	Automotive Products	$	71,376,726	$	56,193,764	$	203,997,815	$	178,803,882
	Other	2,279,520		1,429,591		5,108,341		1,832,668
	Total	$	73,656,246	$	57,623,355	$	209,106,156	$	180,636,550
	Additionally, due to the HomeLink acquisition, the Company is providing certain Asset information by Segment as of September 30, 2013 and December 31, 2012 as shown below:
	Total Assets	As of September 30, 2013		As of December 31, 2012
	Automotive	$	1,298,851,069	$	619,337,527
	Other	9,539,297		8,010,779
	Corporate	388,737,797		638,343,029
	Total Assets	$	1,697,128,163	$	1,265,691,335

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'
Income taxes	'
	Income Taxes
	The effective tax rate was 31.5% in the third quarter of 2013 compared to 32.1% for same period of 2012. The effective tax rate was 31.7% in the first nine months of 2013 compared to 32.5% for the same period of 2012. Effective tax rates differ from statutory federal income tax rates, primarily due to the domestic manufacturing deduction, provisions for state and local income taxes and permanent tax differences. The decrease in the effective tax rate is primarily due to realized benefits of approximately $1 million from the filing of an amended federal tax return for 2009, specifically related to increased Research & Development tax credits.

Business_Combinations_Tables

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Schedule of preliminary allocation of the purchase price	'
	The preliminary allocation of the purchase price through September 30, 2013 is as follows:
	Net Assets Acquired	Fair Value
	Prepaid Service Agreement Costs	$	3,383,000
	Personal Property	4,430,986
	Real Property	1,060,000
	HomeLink Trade Names and Trademarks	47,000,000
	Homelink Technology	166,000,000
	Existing Customer Platforms	43,000,000
	Exclusive Licensing Agreement	87,000,000
	Accounts Receivable	7,719,302
	Net Customer Tooling	956,665
	Fair Value of Acquired Assets	360,549,953
	Goodwill	337,557,061
	Total Cash Consideration	$	698,107,014
Schedule of pro forma information	'
	The following unaudited pro forma condensed consolidated statement of income for nine month periods ended September 30, 2013 and 2012 include pro-forma adjustments to reflect the effect of the acquisition as if it had occurred on January 1, 2013. This unaudited pro forma consolidated statement of income is provided for informational purposes only and does not purport to be indicative of the results which would have actually been attained had the acquisition occurred on January 1, 2013 or that may be attained in the future.
	PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF INCOME
	Nine Months Ended September 30,
		2013		2012
	Net Sales	$	944,550	$	931,221
	Net Income	187,250		159,781

Goodwill_and_Other_Intangible_1

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2013
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule of intangible assets	'
	The Intangible assets as of September 30, 2013 consist of the following:
	Other Intangible Assets	Gross		Accumulated Amortization		Net		Assumed Useful Life
	HomeLink Trade Names and Trademarks	$	47,000,000	—		$	47,000,000	Indefinite
	HomeLink Technology	166,000,000		—		166,000,000		10 to 15 years
	Existing Customer Platforms	43,000,000		—		43,000,000		10 years
	Exclusive Licensing Agreement	87,000,000		—		87,000,000		Indefinite
	Total other identifiable intangible assets	$	343,000,000	$	—	$	343,000,000

Investments_Tables

Investments (Tables)	9 Months Ended
	Sep. 30, 2013
Investments [Abstract]	'
Investment Securities Stated at Fair Value	'
	Assets or liabilities that have recurring measurements are shown below as of September 30, 2013, and December 31, 2012:
				Fair Value Measurements at Reporting Date Using
		Total as of		Quoted Prices in		Significant			Significant
				Active Markets for		Other			Unobservable
				Identical Assets		Observable			Inputs
						Inputs
	Description	30-Sep-13		(Level 1)		(Level 2)			(Level 3)
	Cash & Cash Equivalents	$	226,676,955	$	226,676,955				$	—
	Long-Term Investments:
	Common Stocks	37,646,607		37,646,607		—			—
	Mutual Funds – Equity	76,624,016		76,624,016		—			—
	Total	$	340,947,578	$	340,947,578	$	—		$	—
				Fair Value Measurements at Reporting Date Using
		Total as of		Quoted Prices in		Significant Other			Significant
				Active Markets for		Observable			Unobservable
				Identical Assets		Inputs			Inputs
	Description	31-Dec-12		(Level 1)		(Level 2)			(Level 3)
	Cash & Cash Equivalents	$	389,678,664	$	389,678,664	$	—		$	—
	Short-Term Investments:
	Certificate of Deposit	510,881		—		510,881			—
	Government Securities	38,522,471		—		38,522,471			—
	U.S. Treasury Notes	15,020,350		—		15,020,350			—
	Corporate Bonds	6,563,228		—		6,563,228			—
	Other	185,926		185,926		—			—
	Long-Term Investments:
	Corporate Bonds	2,180,780		—		2,180,780			—
	Common Stocks	53,283,201		53,283,201		—			—
	Mutual Funds – Equity	86,109,053		86,109,053		—			—
	Other – Equity	261,000		261,000		—			—
	Total	$	592,315,554	$	529,517,844	$	62,797,710		$	—
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, 2013, and December 31, 2012:
	As of September 30, 2013:
				Unrealized
		Cost		Gains		Losses			Market Value
	Long-Term Investments:
	Common Stocks	$	27,830,723	$	9,962,493	$	(146,609	)	$	37,646,607
	Mutual Funds – Equity	56,071,512		20,552,504		—			76,624,016
	Total	$	83,902,235	$	30,514,997	$	(146,609	)	$	114,270,623
	As of December 31, 2012:
				Unrealized
		Cost		Gains		Losses			Market Value
	Short-Term Investments:
	Certificate of Deposit	$	510,881	$	—	$	—		$	510,881
	Government Securities	38,514,411		9,004		(944		)	38,522,471
	U.S. Treasury Notes	15,018,810		2,602		(1,062		)	15,020,350
	Corporate Bonds	6,529,758		33,470		—			6,563,228
	Other	185,926		—		—			185,926
	Long-Term Investments:
	Corporate Bonds	2,174,948		5,832		—			2,180,780
	Common Stocks	40,893,121		12,781,501		(391,421		)	53,283,201
	Mutual Funds – Equity	75,321,640		11,082,714		(295,301		)	86,109,053
	Other – Equity	238,506		22,494		—			261,000
	Total	$	179,388,001	$	23,937,617	$	(688,728	)	$	202,636,890
Schedule of Unrealized Loss on Investments	'
	Unrealized losses on investments as of September 30, 2013, are as follows:
		Aggregate Unrealized Losses		Aggregate Fair Value
	Less than one year	$	146,609	$	37,646,607
	Unrealized losses on investments as of December 31, 2012, are as follows:
		Aggregate Unrealized Losses		Aggregate Fair Value
	Less than one year	$	688,728	$	22,887,686

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2013
Inventory Disclosure [Abstract]	'
Schedule of Inventories	'
	Inventories consisted of the following at the respective balance sheet dates:
		September 30, 2013		31-Dec-12
	Raw materials	$	72,278,273	$	114,750,525
	Work-in-process	23,466,112		24,588,734
	Finished goods	21,662,174		20,591,007
	Total Inventory	$	117,406,559	$	159,930,266

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2013
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,
		2013		2012		2013		2012
	Numerators:
	Numerator for both basic and diluted EPS, net income	$	55,520,961	$	41,877,083	$	153,048,925	$	128,988,206
	Denominators:
	Denominator for basic EPS, weighted-average shares outstanding	143,697,760		143,027,693		143,160,402		143,415,077
	Potentially dilutive shares resulting from stock plans	821,140		556,682		655,639		1,002,142
	Denominator for diluted EPS	144,518,900		143,584,375		143,816,041		144,417,219
	Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive	3,220,980		5,332,661		3,573,418		3,289,832

StockBased_Compensation_Plans_

Stock-Based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2013
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				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
	Dividend Yield (1)	2.64	%	2.67	%	2.7	%	2.64	%
	Expected volatility (2)	44.9	%	46.91	%	45.61	%	45.17	%
	Risk-free interest rate (3)	1.39	%	0.64	%	1.19	%	0.79	%
	Expected term of options (years) (4)	4		4.05		4.01		4.04
	Weighted-avg. grant date fair value	$7.61		$5.23		$6.98		$6.09
	(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, 2013
Comprehensive Income [Abstract]	'
Reclassification out of Accumulated Other Comprehensive Income	'
	The following table presents the net changes in the Company's accumulated other comprehensive income by component (1):
		For Three Months Ended September 30,								For Nine Months Ended September 30,
		2013				2012				2013				2012
	Foreign currency translation adjustments:
	Balance at beginning of period	$	2,086,299			$	1,689,750			$	2,458,933			$	2,129,957
	Other Comprehensive income before reclassifications	273,097				275,648				(99,537		)		(164,559		)
	Amounts reclassified from accumulated other comprehensive income	—				—				—				—
	Net current-period change	273,097				275,648				(99,537		)		(164,559		)
	Balance at end of period	2,359,396				1,965,398				2,359,396				1,965,398
	Unrealized gains(losses) on available-for-sale securities:
	Balance at beginning of period	18,700,117				13,422,635				15,111,778				10,412,246
	Other Comprehensive income before reclassifications	5,240,576				4,901,805				13,932,930				10,665,529
	Amounts reclassified from accumulated other comprehensive income	(4,201,241		)		(2,172,986		)		(9,305,256		)		(4,926,321		)
	Net current-period change	1,039,335				2,728,819				4,627,674				5,739,208
	Balance at end of period	19,739,452				16,151,454				19,739,452				16,151,454
	Accumulated other comprehensive income, end of period	$	22,098,848			$	18,116,852			$	22,098,848			$	18,116,852
	(1) All amounts are shown net of tax. Amounts in parentheses indicate debits.
Schedule of Accumulated Other Comprehensive Income (Loss)	'
	The following table presents details of reclassifications out of other comprehensive income for the three and nine months ended September 30, 2013 and 2012.
	Details about Accumulated Other Comprehensive Income Components (2)		Amounts Reclassified from Other Comprehensive Income															Affected Line item in the Statement of Consolidated Income
			For the Three Months ended September 30,								For the Nine Months ended September 30,
			2013				2012				2013				2012
	Unrealized gains and (losses) on available-for-sale securities
	Realized gain (loss) on sale of securities		$	6,463,447			$	3,343,055			$	14,315,778			$	7,578,955		Other, net
	Provision for Income Taxes		(2,262,206		)		(1,170,069		)		(5,010,522		)		(2,652,634		)	Provision for Income Taxes
	Total reclassifications for the period		$	4,201,241			$	2,172,986			$	9,305,256			$	4,926,321		Net of tax
	(2) Amounts in parentheses indicate debits.

Segment_Reporting_Tables

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Schedule of Automotive and Other Segment Reporting	'
	The Company also develops and manufactures variably dimmable 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,
		2013		2012		2013		2012
	Revenue:
	Automotive Products	$	280,924,112	$	261,910,519	$	823,681,484	$	822,415,871
	Other	7,697,514		6,337,570		21,413,009		16,794,528
	Total	$	288,621,626	$	268,248,089	$	845,094,493	$	839,210,399
	Income from operations:
	Automotive Products	$	71,376,726	$	56,193,764	$	203,997,815	$	178,803,882
	Other	2,279,520		1,429,591		5,108,341		1,832,668
	Total	$	73,656,246	$	57,623,355	$	209,106,156	$	180,636,550
	Additionally, due to the HomeLink acquisition, the Company is providing certain Asset information by Segment as of September 30, 2013 and December 31, 2012 as shown below:
	Total Assets	As of September 30, 2013		As of December 31, 2012
	Automotive	$	1,298,851,069	$	619,337,527
	Other	9,539,297		8,010,779
	Corporate	388,737,797		638,343,029
	Total Assets	$	1,697,128,163	$	1,265,691,335

Business_Combinations_Details

Business Combinations (Details) (USD $)	0 Months Ended	3 Months Ended
	Jul. 18, 2013	Sep. 30, 2013
Business Acquisition [Line Items]	'	'
Minimum term in business	'10 years	'
HomeLinkB. [Member]	'	'
Business Acquisition [Line Items]	'	'
Purchase price	$700,000,000	'
Cash paid to aquire business	423,000,000	'
Acquisition-related costs	'	3,121,000
Selling, General and Administrative Expenses [Member] | HomeLinkB. [Member]	'	'
Business Acquisition [Line Items]	'	'
Acquisition-related costs	'	2,167,000
Prepaid Expenses and Other [Member] | HomeLinkB. [Member]	'	'
Business Acquisition [Line Items]	'	'
Debt issuance cost	'	$954,000

Business_Combinations_Schedule

Business Combinations - Schedule of preliminary allocation of the purchase price (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Business Acquisition [Line Items]	'	'
Goodwill	$337,670,463	$0
HomeLinkB. [Member]	'	'
Business Acquisition [Line Items]	'	'
Prepaid Service Agreement Costs	3,383,000	'
Personal Property	4,430,986	'
Real Property	1,060,000	'
Accounts Receivable	7,719,302	'
Net Customer Tooling	956,665	'
Fair Value of Acquired Assets	360,549,953	'
Goodwill	337,557,061	'
Total Cash Consideration	698,107,014	'
HomeLink Trade Names and Trademarks [Member] | HomeLinkB. [Member]	'	'
Business Acquisition [Line Items]	'	'
Indefinite-lived intangible assets	47,000,000	'
Exclusive Licensing Agreement [Member] | HomeLinkB. [Member]	'	'
Business Acquisition [Line Items]	'	'
Indefinite-lived intangible assets	87,000,000	'
HomeLink Technology [Member] | HomeLinkB. [Member]	'	'
Business Acquisition [Line Items]	'	'
Finite-lived intangibles	166,000,000	'
Existing Customer Platforms [Member] | HomeLinkB. [Member]	'	'
Business Acquisition [Line Items]	'	'
Finite-lived intangibles	$43,000,000	'

Business_Combinations_Pro_form

Business Combinations - Pro forma information (Details) (HomeLinkB. [Member], USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
HomeLinkB. [Member]	'	'
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]	'	'
Net Sales	$944,550	$931,221
Net Income	$187,250	$159,781

Goodwill_and_Other_Intangible_2

Goodwill and Other Intangible Assets (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Sep. 30, 2013
			HomeLinkB. [Member]	HomeLinkB. [Member]
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]	'	'	'	'
Goodwill	$337,670,463	$0	$337,557,061	$337,557,061
Goodwill that is expected to be deductible for tax purposes	'	'	337,600,000	337,600,000
Amortization expense	'	'	0	0
Amortization expense, remainder of 2013	'	'	7,600,000	7,600,000
Amortization expense, 2014	'	'	20,800,000	20,800,000
Amortization expense, 2015	'	'	20,800,000	20,800,000
Amortization expense, 2016	'	'	20,800,000	20,800,000
Amortization expense, 2017	'	'	20,800,000	20,800,000
Amortization expense, 2018	'	'	$20,800,000	$20,800,000

Goodwill_and_Other_Intangible_3

Goodwill and Other Intangible Assets - Schedule of intangible assets (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
			HomeLinkB. [Member]	HomeLinkB. [Member]	HomeLinkB. [Member]	HomeLinkB. [Member]	HomeLinkB. [Member]	HomeLinkB. [Member]	HomeLinkB. [Member]
				HomeLink Technology [Member]	HomeLink Technology [Member]	HomeLink Technology [Member]	Existing Customer Platforms [Member]	HomeLink Trade Names and Trademarks [Member]	Exclusive Licensing Agreement [Member]
					Minimum [Member]	Maximum [Member]
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]	'	'	'	'	'	'	'	'	'
Indefinite-lived intangible assets	'	'	'	'	'	'	'	$47,000,000	$87,000,000
Finite-lived intangible assets, gross	'	'	'	166,000,000	'	'	43,000,000	'	'
Finite-lived intangible assets, accumulated amortization	'	'	0	0	'	'	0	'	'
Finite-lived intangible assets, net	'	'	'	166,000,000	'	'	43,000,000	'	'
Intangible assets, gross	'	'	343,000,000	'	'	'	'	'	'
Intangible assets, net	$370,268,798	$29,256,089	$343,000,000	'	'	'	'	'	'
Finite-lived intangible asset, useful life	'	'	'	'	'10 years	'15 years	'10 years	'	'

Investments_Investment_Securit

Investments (Investment Securities Stated at Fair Value) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash & Cash Equivalents	$226,676,955	$389,678,664
Investments	114,270,623	202,636,890
Total	340,947,578	592,315,554
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash & Cash Equivalents	226,676,955	389,678,664
Total	340,947,578	529,517,844
Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash & Cash Equivalents	'	0
Total	0	62,797,710
Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash & Cash Equivalents	0	0
Total	0	0
Short-Term Investments [Member] | Government Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	38,522,471
Short-Term Investments [Member] | Government Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Short-Term Investments [Member] | Government Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	38,522,471
Short-Term Investments [Member] | Government Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Short-Term Investments [Member] | U.S. Treasury Notes [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	15,020,350
Short-Term Investments [Member] | U.S. Treasury Notes [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Short-Term Investments [Member] | U.S. Treasury Notes [Member] | Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	15,020,350
Short-Term Investments [Member] | U.S. Treasury Notes [Member] | Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Short-Term Investments [Member] | Corporate Bond Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	6,563,228
Short-Term Investments [Member] | Corporate Bond Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Short-Term Investments [Member] | Corporate Bond Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	6,563,228
Short-Term Investments [Member] | Corporate Bond Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Short-Term Investments [Member] | Other [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	185,926
Short-Term Investments [Member] | Other [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	185,926
Short-Term Investments [Member] | Other [Member] | Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Short-Term Investments [Member] | Other [Member] | Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Short-Term Investments [Member] | Certificate Of Deposit [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	510,881
Short-Term Investments [Member] | Certificate Of Deposit [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Short-Term Investments [Member] | Certificate Of Deposit [Member] | Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	510,881
Short-Term Investments [Member] | Certificate Of Deposit [Member] | Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Long-Term Investments [Member] | Corporate Bond Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	2,180,780
Long-Term Investments [Member] | Corporate Bond Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Long-Term Investments [Member] | Corporate Bond Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	2,180,780
Long-Term Investments [Member] | Corporate Bond Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Long-Term Investments [Member] | Common Stocks [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	37,646,607	53,283,201
Long-Term Investments [Member] | Common Stocks [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	37,646,607	53,283,201
Long-Term Investments [Member] | Common Stocks [Member] | Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	0	0
Long-Term Investments [Member] | Common Stocks [Member] | Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	0	0
Long-Term Investments [Member] | Mutual Funds - Equity [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	76,624,016	86,109,053
Long-Term Investments [Member] | Mutual Funds - Equity [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	76,624,016	86,109,053
Long-Term Investments [Member] | Mutual Funds - Equity [Member] | Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	0	0
Long-Term Investments [Member] | Mutual Funds - Equity [Member] | Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	0	0
Long-Term Investments [Member] | Other - Equity [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	261,000
Long-Term Investments [Member] | Other - Equity [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	261,000
Long-Term Investments [Member] | Other - Equity [Member] | Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	0
Long-Term Investments [Member] | Other - Equity [Member] | Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Investments	'	$0

Investments_Schedule_of_Amorti

Investments (Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value of Investment Securities) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	$83,902,235	$179,388,001
Unrealized Gains	30,514,997	23,937,617
Unrealized Losses	-146,609	-688,728
Investments	114,270,623	202,636,890
Short-Term Investments [Member] | Government Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	'	38,514,411
Unrealized Gains	'	9,004
Unrealized Losses	'	-944
Investments	'	38,522,471
Short-Term Investments [Member] | U.S. Treasury Notes [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	'	15,018,810
Unrealized Gains	'	2,602
Unrealized Losses	'	-1,062
Investments	'	15,020,350
Short-Term Investments [Member] | Corporate Bond Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	'	6,529,758
Unrealized Gains	'	33,470
Unrealized Losses	'	0
Investments	'	6,563,228
Short-Term Investments [Member] | Other [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	'	185,926
Unrealized Gains	'	0
Unrealized Losses	'	0
Investments	'	185,926
Short-Term Investments [Member] | Certificate Of Deposit [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	'	510,881
Unrealized Gains	'	0
Unrealized Losses	'	0
Investments	'	510,881
Long-Term Investments [Member] | Corporate Bond Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	'	2,174,948
Unrealized Gains	'	5,832
Unrealized Losses	'	0
Investments	'	2,180,780
Long-Term Investments [Member] | Common Stocks [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	27,830,723	40,893,121
Unrealized Gains	9,962,493	12,781,501
Unrealized Losses	-146,609	-391,421
Investments	37,646,607	53,283,201
Long-Term Investments [Member] | Mutual Funds - Equity [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	56,071,512	75,321,640
Unrealized Gains	20,552,504	11,082,714
Unrealized Losses	0	-295,301
Investments	76,624,016	86,109,053
Long-Term Investments [Member] | Other - Equity [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	'	238,506
Unrealized Gains	'	22,494
Unrealized Losses	'	0
Investments	'	$261,000

Investments_Schedule_of_Unreal

Investments (Schedule of Unrealized Loss on Investments) (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Investments [Abstract]	'	'
Aggregate Unrealized Losses, Less than one year	$146,609	$688,728
Aggregate Fair Value, Less than one year	37,646,607	22,887,686
Equity investment losses were considered to be other than temporary	$0	'

Inventories_Schedule_Of_Invent

Inventories (Schedule Of Inventories) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]	'	'
Raw materials	$72,278,273	$114,750,525
Work-in-process	23,466,112	24,588,734
Finished goods	21,662,174	20,591,007
Total Inventory	$117,406,559	$159,930,266

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, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerators [Abstract]	'	'	'	'
Numerator for both basic and diluted EPS, net income	$55,520,961	$41,877,083	$153,048,925	$128,988,206
Denominators [Abstract]	'	'	'	'
Denominator for basic EPS, weighted-average shares outstanding	143,697,760	143,027,693	143,160,402	143,415,077
Potentially dilutive shares resulting from stock plans	821,140	556,682	655,639	1,002,142
Denominator for diluted EPS	144,518,900	143,584,375	143,816,041	144,417,219
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive	3,220,980	5,332,661	3,573,418	3,289,832

StockBased_Compensation_Plans_1

Stock-Based Compensation Plans (Narrative) (Details) (USD $)	3 Months Ended	9 Months Ended		9 Months Ended			1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	31-May-13	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
			Employee Stock Option Plan [Member]	Employee Stock Option Plan [Member]	Employee Stock Option Plan [Member]	Non-Employee Director Stock Option Plan [Member]	Employee Stock Purchase Plan [Member]	Restricted Stock Plan [Member]	Restricted Stock Plan [Member]	Equity Incentive Plans [Member]	Stock Options [Member]
				Minimum [Member]	Maximum [Member]					plan	plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Number of plans (in plans)	'	'	'	'	'	'	'	'	'	4	2
Compensation expense for share-based payments	$3,795,626	$10,529,514	'	'	'	'	'	'	'	'	'
Compensation cost capitalized as part of inventory	'	203,872	'	'	'	'	'	'	'	'	'
Option vesting period	'	'	'	'1 year	'5 years	'6 months	'	'	'	'	'
Option expiration period	'	'	'	'2 years	'7 years	'10 years	'	'	'	'	'
Unrecognized compensation cost	'	'	23,234,157	'	'	96,540	'	'	'	'	'
Options granted (in shares)	'	'	'	'	'	84,000	'	'	'	'	'
Shares approved (in shares)	'	'	'	'	'	'	1,000,000	'	'	'	'
ESPP discount rate	'	'	'	'	'	'	85.00%	'	'	'	'
ESPP discount rate recognized as compensation expense	'	'	'	'	'	'	15.00%	'	'	'	'
Options granted (in shares)	'	'	'	'	'	'	'	2,000,000	2,000,000	'	'
Restricted period, maximum, in years	'	'	'	'	'	'	'	'	'10 years	'	'
Unearned stock-based compensation	'	'	'	'	'	'	'	9,867,574	9,867,574	'	'
Amortization expense	'	'	'	'	'	'	'	$654,683	$1,998,750	'	'

StockBased_Compensation_Plans_2

Stock-Based Compensation Plans (Weighted-Average Assumptions for the ESOP) (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'		'		'		'
Dividend yield	2.64%	[1]	2.67%	[1]	2.70%	[1]	2.64%	[1]
Expected volatility	44.90%	[2]	46.91%	[2]	45.61%	[2]	45.17%	[2]
Risk-free interest rate	1.39%	[3]	0.64%	[3]	1.19%	[3]	0.79%	[3]
Expected term of options	'4 years	[4]	'4 years 18 days	[4]	'4 years 3 days	[4]	'4 years 15 days	[4]
Weighted-avg. grant-date fair value (in dollars per share)	$7.61		$5.23		$6.98		$6.09
[1]	Represents the Companybs estimated cash dividend yield over the expected term of option grant.
[2]	Amount is determined based on analysis of historical price volatility of the Companybs 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_AOCI_Roll

Comprehensive Income (AOCI Rollforward) (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'		'		'
Balance at beginning of period	'		'		$17,570,711		'
Comprehensive Income	56,833,393		44,881,549		157,577,062		134,562,853
Balance at end of period	22,098,848	[1]	18,116,852	[1]	22,098,848	[1]	18,116,852	[1]
Foreign currency translation adjustments [Member]	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'		'		'
Balance at beginning of period	2,086,299	[1]	1,689,750	[1]	2,458,933	[1]	2,129,957	[1]
Other Comprehensive income before reclassifications	273,097	[1]	275,648	[1]	-99,537	[1]	-164,559	[1]
Amounts reclassified from accumulated other comprehensive income	0	[1]	0	[1]	0	[1]	0	[1]
Comprehensive Income	273,097	[1]	275,648	[1]	-99,537	[1]	-164,559	[1]
Balance at end of period	2,359,396	[1]	1,965,398	[1]	2,359,396	[1]	1,965,398	[1]
Unrealized gains(losses) on available-for-sale securities [Member]	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'		'		'
Balance at beginning of period	18,700,117	[1]	13,422,635	[1]	15,111,778	[1]	10,412,246	[1]
Other Comprehensive income before reclassifications	5,240,576	[1]	4,901,805	[1]	13,932,930	[1]	10,665,529	[1]
Amounts reclassified from accumulated other comprehensive income	-4,201,241	[1]	-2,172,986	[1]	-9,305,256	[1]	-4,926,321	[1]
Comprehensive Income	1,039,335	[1]	2,728,819	[1]	4,627,674	[1]	5,739,208	[1]
Balance at end of period	$19,739,452	[1]	$16,151,454	[1]	$19,739,452	[1]	$16,151,454	[1]
[1]	All amounts are shown net of tax. Amounts in parentheses indicate debits.

Comprehensive_Income_Reclassif

Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Provision for Income Taxes	($25,522,293)		($19,808,978)		($70,877,180)		($62,164,893)
Amounts Reclassified from Other Comprehensive Income [Member] | Unrealized gains(losses) on available-for-sale securities [Member]	'		'		'		'
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Realized gain (loss) on sale of securities	6,463,447	[1]	3,343,055	[1]	14,315,778	[1]	7,578,955	[1]
Provision for Income Taxes	-2,262,206	[1]	-1,170,069	[1]	-5,010,522	[1]	-2,652,634	[1]
Total reclassifications for the period	$4,201,241	[1]	$2,172,986	[1]	$9,305,256	[1]	$4,926,321	[1]
[1]	Amounts in parentheses indicate debits.

Debt_and_Financing_Arrangement1

Debt and Financing Arrangements (Details) (USD $)	0 Months Ended	3 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 27, 2013
Base Rate [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Description of variable rate basis	'base	'	'
Basis spread on variable rate	'	'	0.50%
LIBOR Rate [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Description of variable rate basis	'LIBOR	'LIBOR	'
Basis spread on variable rate	1.18%	1.18%	1.00%
Minimum [Member] | Base Rate [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Basis spread on variable rate	'	'	0.00%
Minimum [Member] | LIBOR Rate [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Basis spread on variable rate	'	'	1.00%
Maximum [Member] | Base Rate [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Basis spread on variable rate	'	'	0.75%
Maximum [Member] | LIBOR Rate [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Basis spread on variable rate	'	'	1.75%
Credit Agreement [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Additional principal amount available	'	'	75,000,000
Amount borrowed	275,000,000	275,000,000	'
Available borrowing capacity	25,000,000	25,000,000	'
Revolving Facility [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Principal amount	'	'	150,000,000
Amount borrowed	125,000,000	125,000,000	'
Term Loan [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Principal amount	'	'	150,000,000
Amount borrowed	150,000,000	150,000,000	'
Swing Loans [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Additional principal amount available	'	'	20,000,000
Letters of Credit [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Additional principal amount available	'	'	20,000,000

Equity_Details

Equity (Details) (USD $)	9 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2013	Mar. 31, 2013
Equity [Abstract]	'	'
Common stock issued under stock compensation plan (in shares)	1,654,477	'
Increase in cash dividend rate (in dollars per share)	'	$0.01
Dividends payable (in dollars per share)	$0.14	$0.14
Dividends payable	$20.30	'

Segment_Reporting_Schedule_Of_

Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenue	$288,621,626	$268,248,089	$845,094,493	$839,210,399	'
Income (loss) from operations	73,656,246	57,623,355	209,106,156	180,636,550	'
Assets	1,697,128,163	'	1,697,128,163	'	1,265,691,335
Automotive Products [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenue	280,924,112	261,910,519	823,681,484	822,415,871	'
Income (loss) from operations	71,376,726	56,193,764	203,997,815	178,803,882	'
Assets	1,298,851,069	'	1,298,851,069	'	619,337,527
Other [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenue	7,697,514	6,337,570	21,413,009	16,794,528	'
Income (loss) from operations	2,279,520	1,429,591	5,108,341	1,832,668	'
Assets	9,539,297	'	9,539,297	'	8,010,779
Corporate [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Assets	$388,737,797	'	$388,737,797	'	$638,343,029

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]	'	'	'	'
Effective income tax rate	31.50%	32.10%	31.70%	32.50%
Realized tax benfits from amended return	'	'	$1	'