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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2019	Feb. 01, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	000-10235
Entity Registrant Name	GENTEX CORPORATION
Entity Incorporation, State or Country Code	MI
Entity Tax Identification Number	38-2030505
Entity Address, Address Line One	600 N. Centennial Street,
Entity Address, State or Province	MI
Entity Address, Postal Zip Code	49464
Entity Address, City or Town	Zeeland,
City Area Code	616
Local Phone Number	772-1800
Title of 12(b) Security	Common Stock, par value $.06 per share
Trading Symbol	GNTX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Public Float			$ 6,258,471,128
Entity Common Stock, Shares Outstanding		251,274,340
Entity Filer Category	Large Accelerated Filer
Entity Central Index Key	0000355811
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Amendment Flag	false

Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
CURRENT ASSETS:
Cash and cash equivalents	$ 296,321,622	$ 217,025,278
Short-term investments	140,384,053	169,412,999
Accounts receivable, net	235,410,326	213,537,799
Inventories, net	248,941,855	225,281,599
Prepaid expenses and other	29,319,036	25,672,579
Total current assets	950,376,892	850,930,254
PLANT AND EQUIPMENT:
Land, buildings and improvements	344,231,180	340,910,332
Machinery and equipment	843,439,691	838,887,032
Construction-in-process	39,456,490	18,156,423
Total Plant and Equipment	1,227,127,361	1,197,953,787
Less- Accumulated depreciation	(728,811,261)	(699,480,021)
Net Plant and Equipment	498,316,100	498,473,766
OTHER ASSETS:
Goodwill	307,365,845	307,365,845
Long-term investments	139,909,323	137,979,082
Intangible assets, net	250,375,000	269,675,000
Patents and other assets, net	22,460,033	21,010,121
Total Other Assets	720,110,201	736,030,048
TOTAL ASSETS	2,168,803,193	2,085,434,068
CURRENT LIABILITIES:
Accounts payable	97,553,917	92,810,316
Accrued liabilities:
Salaries, wages and vacation	16,385,833	15,860,073
Income taxes	24,952	4,293,608
Royalties	17,371,829	16,174,041
Dividends payable	28,896,914	28,526,147
Other	11,613,355	11,496,734
Total current liabilities	171,846,800	169,160,919
OTHER NON-CURRENT LIABILITIES	7,414,424	0
DEFERRED INCOME TAXES	51,454,149	54,521,489
TOTAL LIABILITIES	230,715,373	223,682,408
SHAREHOLDERS’ INVESTMENT:
Common stock, par value $.06 per share; 400,000,000 shares authorized; 251,277,515 and 259,328,613 shares issued and outstanding in 2019 and 2018 respectively.	15,076,651	15,559,717
Additional paid-in capital	807,928,139	745,324,144
Retained earnings	1,116,372,133	1,102,468,137
Accumulated other comprehensive income:
Unrealized gain on investments	1,095,486	74,549
Cumulative translation adjustment	(2,384,589)	(1,674,887)
Total shareholders’ investment	1,938,087,820	1,861,751,660
TOTAL LIABILITES AND SHAREHOLDERS' INVESTMENT	$ 2,168,803,193	$ 2,085,434,068

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.06	$ 0.06
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	251,277,515	259,328,613
Common stock, shares outstanding (in shares)	251,277,515	259,328,613

Consolidated Statements of Income - USD ($)	12 Months Ended
Consolidated Statements of Income - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
NET SALES	$ 1,858,897,406	$ 1,834,063,697	$ 1,794,872,578
COST OF GOODS SOLD	1,170,589,437	1,143,597,005	1,100,344,312
Gross profit	688,307,969	690,466,692	694,528,266
OPERATING EXPENSES:
Engineering, research and development	114,687,309	107,134,862	99,726,438
Selling, general and administrative	85,083,056	75,206,283	71,443,476
Total operating expenses	199,770,365	182,341,145	171,169,914
Income from operations	488,537,604	508,125,547	523,358,352
OTHER INCOME:
Investment income	11,230,696	11,262,385	9,442,387
Other income (expense), net	647,034	2,659,015	(1,004,035)
Total other income	11,877,730	13,921,400	8,438,352
Income before provision for income taxes	500,415,334	522,046,947	531,796,704
PROVISION FOR INCOME TAXES	75,731,395	84,163,850	125,004,782
NET INCOME	$ 424,683,939	$ 437,883,097	$ 406,791,922
EARNINGS PER SHARE:
Basic (in dollars per share)	$ 1.67	$ 1.64	$ 1.42
Diluted (in dollars per share)	1.66	1.62	1.41
Cash Dividends Declared per Share (in dollars per share)	$ 0.460	$ 0.440	$ 0.390

Consolidated Statements of Comprehensive Income - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 424,683,939	$ 437,883,097	$ 406,791,922
Other comprehensive income (loss) before tax:
Foreign currency translation adjustments	(709,702)	(2,319,917)	3,508,029
Unrealized gains on derivatives	0	98,767	1,721,933
Unrealized gains on available-for-sale securities, net	1,292,325	115,059	5,903,699
Other comprehensive income (loss), before tax	582,623	(2,106,091)	11,133,661
Expense for income taxes related to components of other comprehensive income (loss)	271,388	44,903	2,668,973
Other comprehensive income (loss), net of tax	311,235	(2,150,994)	8,464,688
Comprehensive income	$ 424,995,174	$ 435,732,103	$ 415,256,610

Consolidated Statements of Shareholders' Investment - USD ($)	3 Months Ended				12 Months Ended
	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		259,328,613			259,328,613
Beginning balance		$ 1,861,751,660		$ 2,049,518,261	$ 1,861,751,660	$ 2,049,518,261	$ 1,910,424,234
Issuance of common stock					77,821,151	66,837,820	47,770,467
Repurchases of common stock					(331,471,392)	(591,577,851)	(231,363,216)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock					21,671,192	18,305,981	18,376,965
Impact of ASU 2016-01 adoption						0
Dividends declared					(116,679,965)	(117,064,654)	(110,946,799)
Net income	$ 99,547,000	$ 104,280,000	$ 106,275,000	$ 111,249,000	424,683,939	437,883,097	406,791,922
Other comprehensive income					$ 311,235	$ (2,150,994)	8,464,688
Ending balance (in shares)	251,277,515		259,328,613		251,277,515	259,328,613
Ending balance	$ 1,938,087,820		$ 1,861,751,660		$ 1,938,087,820	$ 1,861,751,660	$ 2,049,518,261
Common Stocks
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		259,328,613		280,281,321	259,328,613	280,281,321	287,737,516
Beginning balance		$ 15,559,717		$ 16,816,879	$ 15,559,717	$ 16,816,879	$ 17,264,251
Issuance of common stock (in shares)					5,724,840	5,496,659	4,498,729
Issuance of common stock					$ 343,490	$ 329,801	$ 269,923
Repurchases of common stock (in shares)					(13,775,938)	(26,449,367)	(11,954,924)
Repurchases of common stock					$ (826,556)	$ (1,586,963)	$ (717,295)
Ending balance (in shares)	251,277,515		259,328,613		251,277,515	259,328,613	280,281,321
Ending balance	$ 15,076,651		$ 15,559,717		$ 15,076,651	$ 15,559,717	$ 16,816,879
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		745,324,144		723,510,672	745,324,144	723,510,672	683,446,463
Issuance of common stock					77,477,661	66,508,019	47,500,544
Repurchases of common stock					(36,544,858)	(63,000,528)	(25,813,300)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock					21,671,192	18,305,981	18,376,965
Ending balance	807,928,139		745,324,144		807,928,139	745,324,144	723,510,672
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		1,102,468,137		1,301,997,327	1,102,468,137	1,301,997,327	1,210,984,825
Repurchases of common stock					(294,099,978)	(526,990,360)	(204,832,621)
Impact of ASU 2016-01 adoption						6,642,727
Dividends declared					(116,679,965)	(117,064,654)	(110,946,799)
Net income					424,683,939	437,883,097	406,791,922
Ending balance	1,116,372,133		1,102,468,137		1,116,372,133	1,102,468,137	1,301,997,327
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		$ (1,600,338)		$ 7,193,383	(1,600,338)	7,193,383	(1,271,305)
Impact of ASU 2016-01 adoption						(6,642,727)
Other comprehensive income					311,235	(2,150,994)	8,464,688
Ending balance	$ (1,289,103)		$ (1,600,338)		$ (1,289,103)	$ (1,600,338)	$ 7,193,383

Consolidated Statements of Shareholders' Investment (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividends declared per share (in dollars per share)	$ 0.460	$ 0.440	$ 0.390

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income	$ 424,683,939	$ 437,883,097	$ 406,791,922
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	104,702,974	102,186,814	99,570,908
Gain on disposal of assets	(155,150)	(577,200)	(188,150)
Loss on disposal of assets	588,941	108,927	299,174
Gain on sale of investments	(660,643)	(2,538,729)	(1,309,166)
Loss on sale of investments	176,360	532,494	375,388
Deferred income taxes	(3,358,537)	(4,414,739)	(14,996,179)
Stock based compensation expense related to employee stock options, employee stock purchases and restricted stock	21,671,192	18,305,981	18,376,965
Change in operating assets and liabilities:
Accounts receivable	(21,872,527)	17,583,989	(19,530,043)
Inventories	(23,660,256)	(8,516,016)	(27,454,146)
Prepaid expenses and other	(3,646,457)	(11,268,677)	16,183,673
Accounts payable	4,743,601	2,911,849	9,934,837
Accrued liabilities	2,753,427	220,856	12,947,597
Net cash flows from operating activities	505,966,864	552,418,646	501,002,780
Activity in available-for-sale securities:
Sales proceeds	57,139,135	55,248,551	30,207,523
Maturities and calls	125,013,589	181,892,136	23,100,000
Purchases	(153,257,603)	(332,106,362)	(29,874,960)
Plant and equipment additions	(84,580,255)	(85,990,570)	(104,040,919)
Proceeds from sale of plant and equipment	2,001,315	738,093	249,757
(Increase) Decrease in other assets	(3,027,263)	(5,603,042)	2,646,029
Net cash used for investing activities	(56,711,082)	(185,821,194)	(77,712,570)
CASH FLOWS USED FOR FINANCING ACTIVITIES:
Repayment of long-term debt	0	(78,000,000)	(107,625,000)
Issuance of common stock from stock plan transactions	77,821,151	66,837,820	47,770,467
Cash dividends paid	(116,309,197)	(116,566,639)	(108,815,040)
Repurchases of common stock	(331,471,392)	(591,577,851)	(231,363,216)
Net cash used for financing activities	(369,959,438)	(719,306,670)	(400,032,789)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	79,296,344	(352,709,218)	23,257,421
CASH AND CASH EQUIVALENTS, Beginning of year	217,025,278	569,734,496	546,477,075
CASH AND CASH EQUIVALENTS, End of year	$ 296,321,622	$ 217,025,278	$ 569,734,496

Summary of Significant Accounting and Reporting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Summary Of Significant Accounting And Reporting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES

The Company

Gentex Corporation including its wholly-owned subsidiaries (the "Company") is a leading supplier of digital vision, connected car, dimmable glass, and fire protection products. The Company’s largest business segment involves designing, developing, manufacturing, marketing, and supplying automatic-dimming rearview and non-dimming mirrors and various electronic modules for the automotive industry. The Company ships its product to all of the major automotive producing regions worldwide, which it supports with numerous sales, engineering and distribution locations worldwide.

A substantial portion of the Company’s net sales and accounts receivable result from transactions with domestic and foreign automotive manufacturers and Tier 1 suppliers. The Company also designs, develops, manufactures, markets, and supplies dimmable aircraft windows for the aviation industry and commercial smoke alarms and signaling devices for the fire protection products industry. The Company does not require collateral or other security for trade accounts receivable.

Significant accounting policies of the Company not described elsewhere are as follows:

Consolidation

The consolidated financial statements include the accounts of Gentex Corporation and all of its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated.

Cash Equivalents

Cash equivalents consist of funds invested in bank accounts and money market funds that have daily liquidity.

Allowance For Doubtful Accounts

The Company reviews a monthly aging report of all accounts receivable balances starting with invoices outstanding over sixty days. In addition, the Company monitors information about its customers through a variety of sources including the media, and information obtained through on-going interaction between Company personnel and the customer. Based on the evaluation of the above information, the Company estimates its allowances related to customer receivables on historical credit and collections experience, customers current financial condition and the specific identification of other potential problems, including the economic climate. Actual collections can differ, requiring adjustments to the allowances, but historically such adjustments have not been material.

The following table presents the activity in the Company’s allowance for doubtful accounts:



	Beginning Balance		Net Additions/ (Reductions) to Costs and Expenses		Deductions and Other Adjustments			Ending Balance
Year Ended December 31, 2019:
Allowance for Doubtful Accounts	$	2,746,647	$	—	$	(295,354	)	$	2,451,293
Year Ended December 31, 2018:
Allowance for Doubtful Accounts	$	2,714,533	$	—	$	32,114		$	2,746,647
Year Ended December 31, 2017:
Allowance for Doubtful Accounts	$	2,917,424	$	—	$	(202,891	)	$	2,714,533

The Company’s allowance for doubtful accounts primarily relates to financially distressed automotive customers. The Company continues to work with these financially distressed customers in collecting past due balances.

Investments

The Company follows the provisions of ASC 820, Fair Value Measurements and Disclosures, for its financial assets and liabilities, and for its non-financial assets and liabilities subject to fair value measurements. ASC 820 provides a framework for measuring the fair value of assets and liabilities. This framework is intended to provide increased consistency in how fair value determinations are made under various existing accounting standards that permit, or in some cases, require estimates of fair-market value. This standard also expanded financial statement disclosure requirements about a company’s use of fair-value measurements, including the effect of such measurement on earnings. The cost of securities sold is based on the specific identification method.

The Company determines the fair value of its government securities, asset-backed securities, corporate bonds, and certain mutual funds by utilizing monthly valuation statements that are provided by its broker. The broker determines the investment valuation by utilizing the bid price in the market and also refers to third party sources to validate valuations, and as such are classified as Level 2 assets.

The Company's certificates of deposit are classified as available for sale, and are considered as Level 1 assets. These investments are carried at cost, which approximates fair value.

The Company will also periodically make technology investments in certain non-consolidated third-parties. These equity investments are accounted for in accordance with ASC 321, Investments - Equity Securities. Equity investments that do not have readily determinable fair values, and where the Company has not identified any observable events that would cause adjustment of the valuation to date, are held at cost. These technology investments totaled $9.0 million and $3.9 million as of December 31, 2019 and December 31, 2018, respectively. These investments are classified within Long-Term Investments in the consolidated balance sheet and are not included within the tables below.

Assets or liabilities that have recurring fair value measurements are shown below as of December 31, 2019 and December 31, 2018:



			Fair Value Measurements at Reporting Date Using
	Total as of		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	December 31, 2019		(Level I)		(Level 2)		(Level 3)
Cash & Cash Equivalents	$	296,321,622	$	296,321,622	$	—	$	—
Short-Term Investments:
Certificate of Deposit	50,099,795		50,099,795		—		—
Corporate Bonds	29,219,685		—		29,219,685		—
Government Securities	58,432,823		—		58,432,823		—
Other	2,631,750		2,631,750		—		—
Long-Term Investments:
Asset-backed Securities	25,791,029		—		25,791,029		—
Certificate of Deposit	3,557,798		3,557,798		—		—
Corporate Bonds	22,815,998		—		22,815,998		—
Government Securities	6,088,190		—		6,088,190		—
Municipal Bonds	72,638,690		—		72,638,690		—
Total	$	567,597,380	$	352,610,965	$	214,986,415	$	—



			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, 2018		(Level I)		(Level 2)		(Level 3)
Cash & Cash Equivalents	217,025,278		$	217,025,278	$	—	$	—
Short-Term Investments:
Certificate of Deposit	150,299,384		150,299,384		—		—
Corporate Bonds	6,967,700		—		6,967,700		—
Government Securities	9,176,227		—		9,176,227		—
Other	2,219,688		2,219,688		—		—
Long-Term Investments:
Corporate Bonds	60,369,930		—		60,369,930		—
Municipal Bonds	18,025,432		—		18,025,432		—
Government Securities	56,483,720		—		56,483,720		—
Total	$	520,567,359	$	369,544,350	$	151,023,009	$	—

The amortized cost, unrealized gains and losses, and market value of investment securities are shown as of December 31, 2019 and 2018:



	Unrealized
2019	Cost		Gains		Losses			Market Value
Short-Term Investments:
Certificate of Deposit	$	50,099,795	$	—	$	—		$	50,099,795
Corporate Bonds	29,025,624		194,061		—			29,219,685
Government Securities	58,343,911		99,917		(11,005		)	58,432,823
Other	2,631,750		—		—			2,631,750
Long-Term Investments:
Asset-backed Securities	25,971,156		—		(180,127		)	25,791,029
Certificate of Deposit	3,500,000		58,808		(1,010		)	3,557,798
Corporate Bonds	22,306,130		509,868		—			22,815,998
Government Securities	6,012,705		75,485		—			6,088,190
Municipal Bonds	71,997,996		1,036,116		(395,422		)	72,638,690
Total	$	269,889,067	$	1,974,255	$	(587,564	)	$	271,275,758



	Unrealized
2018	Cost		Gains		Losses			Market Value
Short-Term Investments:
Certificate of Deposit	$	150,299,384	$	—	$	—		$	150,299,384
Government Securities	9,186,586		—		(10,359		)	9,176,227
Corporate Bonds	6,981,305		—		(13,605		)	6,967,700
Other	2,219,688		—		—			2,219,688
Long-Term Investments:
Corporate Bonds	60,659,498		50,340		(339,908		)	60,369,930
Common Stocks	—		—		—			—
Municipal Bonds	17,840,518		184,914		—			18,025,432
Government Securities	56,280,552		205,553		(2,385		)	56,483,720
Total	$	303,467,531	$	440,807	$	(366,257	)	$	303,542,081

Unrealized losses on investments as of December 31, 2019 are as follows:



	Aggregate Unrealized Losses		Aggregate Fair Value
Less than one year	$	587,564	$	90,721,081
Greater than one year	—		—
Total	$	587,564	$	90,721,081

Unrealized losses on investments as of December 31, 2018 are as follows:



	Aggregate Unrealized Losses		Aggregate Fair Value
Less than one year	$	365,824	$	68,722,980
Greater than one year	433		3,000,000
Total	$	366,257	$	71,722,980

ASC 320, Accounting for Certain Investments in Debt and Equity Securities, as amended and interpreted, provides guidance on determining when an investment is other-than-temporarily impaired. The Company reviews its fixed income investments 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 new cost basis in the investment is established. If market, industry, and/or investee conditions deteriorate, the Company may incur future impairments. No investments were considered to be other-than-temporarily impaired in 2019 and 2018.

Fixed income securities as of December 31, 2019, have contractual maturities as follows:



Due within one year	$	137,752,302
Due between one and five years	43,125,222
Due over five years	87,766,483
	$	268,644,007

Fair Value of Financial Instruments

The Company’s financial instruments consist of cash and cash equivalents, investments, accounts receivable, accounts payable, and short and long-term debt. The Company’s estimate of the fair values of these financial instruments approximates their carrying amounts at December 31, 2019 and 2018.

Inventories

Inventories include material, direct labor and manufacturing overhead and are valued at the lower of first-in, first-out (FIFO) cost or net realizable value. Inventories consisted of the following as of December 31, 2019 and 2018:



	2019		2018
Raw materials	$	164,974,553	$	139,058,541
Work-in-process	33,069,255		35,386,615
Finished goods	50,898,047		50,836,443
Total Inventory	$	248,941,855	$	225,281,599

Estimated inventory allowances for slow-moving and obsolete inventories are based on current assessments of future demands, market conditions, evaluation of longer lead times for certain electronic components and related management initiatives. If market conditions or customer requirements change and are less favorable than those projected by management, inventory allowances are adjusted accordingly. Allowances for slow-moving and obsolete inventories (which are included, net, in the above inventory values) were $7.6 million and $7.8 million at December 31, 2019 and 2018, respectively.

Plant and Equipment

Plant and equipment is stated at cost. Depreciation and amortization are computed for financial reporting purposes using the straight-line method, with estimated useful lives of 7 to 30 years for buildings and improvements, and 3 to 10 years for machinery and equipment. Depreciation expense was approximately $82.3 million, $79.7 million and $77.0 million in 2019, 2018 and 2017, respectively.

Impairment or Disposal of Long-Lived Assets

The Company reviews long-lived assets, including property, plant and equipment and other intangible assets with definite lives, for impairment whenever events or changes in circumstances indicate that the asset’s carrying amount may not be recoverable. The Company conducts its long-lived asset impairment analysis in accordance with ASC 360-10-15, Impairment or Disposal of Long-Lived Assets. ASC 360-10-15 requires the Company to group assets and liabilities at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities and evaluate the asset group against the sum of the undiscounted future cash flows. If the undiscounted cash flows do not indicate the carrying amount of the asset is recoverable, an impairment charge is measured as the amount by which the carrying amount of the asset group exceeds its fair value based on discounted cash flow analysis or appraisals.

Patents

The Company’s policy is to capitalize costs incurred to obtain patents. The cost of patents is amortized over their useful lives. The cost of patents in process is not amortized until issuance. The Company periodically obtains intellectual property rights, in the ordinary course of business, and the cost of the rights are amortized over their useful lives.

Goodwill and Intangible Assets

Goodwill reflects the cost of an acquisition in excess of the fair values assigned to identifiable net assets acquired. The Company reviews goodwill for impairment during the fourth quarter on an annual basis or more frequently if events or changes in circumstances indicate that goodwill might be impaired. The Company performs an impairment review for its automotive reporting unit, which has been determined to be one of the Company’s reportable segments, using either a qualitative approach or quantitative approach which utilizes

a fair value method that incorporates certain assumptions and judgments. The fair value of a reporting unit refers to the price that would be received to sell the unit as a whole in an orderly transaction between market participants at the measurement date. The Company performs a qualitative assessment (step 0) to determine whether it is more likely than not that a reporting unit's fair value is less than its carrying amount. If not, no further goodwill impairment testing is performed. If so, we determine the fair value of the reporting unit using step 1 and step 2 tests. If the fair value of the reporting unit is greater than its carrying amount, goodwill is not considered to be impaired. However, if the fair value of the reporting unit is less than its carrying amount, an impairment change is recorded as the excess of the reporting units carrying value over its fair value.

The assumptions included in the impairment tests require judgment and changes to these inputs could impact the results of the calculations which could result in an impairment charge in future periods if the carrying amount of the reporting unit exceeds its calculated fair value. For the qualitative assessment performed, management considers factors such as macro-economic conditions, industry and market considerations, overall financial performance, and other company-specific events, amongst other factors, in making the determination as to whether it is more likely than not that a reporting unit's fair value is less than its carrying amount. Other than management's internal projections of future cash flows, the primary assumptions used in the step 1 and step 2 impairment tests are the weighted-average cost of capital and long-term growth rates. Although the Company's cash flow forecasts are based on assumptions that are considered reasonable by management and consistent with the plans and estimates management is using to operate the underlying business, there are significant judgments in determining the expected future cash flows attributable to a reporting unit. There have been no impairment charges recorded currently or in prior periods in which goodwill existed.

Indefinite lived intangible assets are also subject to annual impairment testing or more frequently if indicators of impairment are identified. Management judgment and assumptions are required in determining the underlying fair value of the indefinite lived intangible assets. While the Company believes the judgments and assumptions used in determining fair value are reasonable, different assumptions could change the estimated fair values and, therefore, impairment charges could be required, which could be material to the consolidated financial statements. The indefinite lived intangible assets were not impaired as a result of the annual test prepared by management for either period presented.

Refer to Note 10, "Goodwill and Intangible Assets" for information regarding the impairment testing performed in calendar year 2019.

Revenue Recognition

The Company recognizes revenue in accordance with Accounting Standards Codification (ASC) 606, Revenue from Contracts with Customers. Accordingly, revenue is recognized in an amount that reflects the consideration to which the Company expects to be entitled in exchange for promised goods or services when it transfers those goods or services to customers. Sales are shown net of returns, which have not historically been significant. The Company does not generate sales from arrangements with multiple deliverables. The Company generally receives purchase orders from customers on an annual basis. Typically, such purchase order provide the annual terms, including pricing, related to a particular vehicle model. Purchase orders generally do not specify quantities. The Company recognizes revenue based on the pricing terms included in our annual purchase orders.

As part of certain agreements, entered into in the ordinary course of business, the Company is asked to provide customers with annual price reductions. Such amounts are subject to estimate and are accrued as a reduction of revenue as products are shipped to those customers. For any shipments of product that may be subject to retroactive price adjustments that are then being negotiated, the Company records revenue based on the Company’s best estimate of the amount of consideration to which the entity will be entitled in exchange for transferring the promised goods to the customer. The Company's best estimate requires significant judgment based on historical results and expected outcomes of ongoing negotiations with customers. The Company's approach is to consider these adjustments to the contract price as variable consideration which is estimated based on the then most likely price amount. In addition, the Company has ongoing adjustments to our pricing arrangements with customers based on the related content, the cost of our products and other commercial

factors. Such pricing accruals are adjusted as they are settled with our customers. Refer to Note 11, "Revenue", for further information.

Advertising and Promotional Materials

All advertising and promotional costs are expensed as incurred and amounted to approximately $3.0 million, $2.5 million and $2.6 million, in 2019, 2018 and 2017, respectively.

Repairs and Maintenance

Major renewals and improvements of property and equipment are capitalized, and repairs and maintenance are expensed as incurred. The Company incurred expenses relating to the repair and maintenance of plant and equipment of approximately $28.9 million, $28.9 million and $24.6 million, in 2019, 2018 and 2017, respectively.

Self-Insurance

The Company is self-insured for a portion of its risk on workers’ compensation and employee medical costs. The arrangements provide for stop loss insurance to manage the Company’s risk. Such costs are accrued based on known claims and an estimate of incurred, but not reported (IBNR) claims. IBNR claims are estimated using historical lag information and other data provided by claims administrators. This estimation process is subjective, and to the extent that future results differ from original estimates, adjustments to recorded accruals may be necessary.

Product Warranty

The Company periodically incurs product warranty costs. Any liabilities associated with product warranty are estimated based on known facts and circumstances and are not significant at December 31, 2019, 2018 and 2017. The Company does not offer extended warranties on its products.

Income Taxes

The provision for income taxes is based on the earnings reported in the consolidated financial statements. Deferred income tax assets and liabilities are computed for differences between the financial statement and tax basis of assets and liabilities that will result in deductible or taxable amounts in the future. Such deferred income tax asset and liability computations are based on enacted tax laws and rates. The Company applies the provisions of ASC 740, Income Taxes, as it relates to uncertainty in income taxes recognized in the Company’s consolidated financial statements. A threshold of more likely than not to be sustained upon examination is applied to uncertain tax positions. The Company deems the estimates related to this provision to be reasonable, however, no assurance can be given that the final outcome of these matters will not vary from what is reflected in the historical income tax provisions and accruals.

Leases

The Company has operating leases for corporate offices, warehouses, vehicles, and other equipment, which are included within "Plant and Equipment" section of the Consolidated Balance Sheets. The leases have remaining lease terms of 1 year to 5 years. The weighted average remaining lease term for operating leases as of December 31, 2019 was 2 years, with a weighted average discount rate of 2.9%. Future minimum lease payments for operating leases as of December 31, 2019 were as follows:



Year ending December 31,

2020	$	786,807
2021	297,316
2022	145,154
2023	19,296
Thereafter	15,105
Total future minimum lease payments	$	1,263,678
Less imputed interest	(84,964		)
Total	$	1,178,714

Earnings Per Share

The Company has unvested share-based payment awards with a right to receive non-forfeitable dividends, which are considered participating securities under ASC 260, Earnings Per Share. The Company allocates earnings to participating securities and computes earnings per share using the two-class method. Under the two-class method, net income per share is computed by dividing net income allocated to common shareholders by the weighted average number of common shares outstanding for the period. In applying the two-class method, net income is allocated to both common shares and participating securities based on their respective weighted average shares outstanding for the period.

The following table sets forth the computation of basic and diluted net income per common share under the two-class method for each of the last three years:



	2019		2018		2017
Basic Earnings Per Share
Net Income	$	424,683,939	$	437,883,097	$	406,791,922
Less: Allocated to participating securities⁽¹⁾	5,028,813		—		—
Net Income available to common shareholders	$	419,655,126	$	437,883,097	$	406,791,922

Basic weighted average shares outstanding	251,766,382		267,794,786		285,864,997
Net Income per share - Basic	$	1.67	$	1.64	$	1.42

Diluted Earnings Per Share
Allocation of Net Income used in basic computation	$	419,655,126	$	437,883,097	$	406,791,922
Reallocation of undistributed earnings	21,104		21,007		19,398
Net Income available to common shareholders - Diluted	$	419,676,230	$	437,904,104	$	406,811,320

Number of shares used in basic computation	251,766,382		267,794,786		285,864,997
Additional weighted average dilutive common stock equivalents	1,506,608		2,082,563		2,361,092
Diluted weighted average shares outstanding	253,272,990		269,877,349		288,226,089

Net income per share - Diluted	$	1.66	$	1.62	$	1.41

⁽¹⁾While there were participating securities in 2018 and 2017, they did not have a material impact on the two-class EPS calculation. Net income allocated to participating securities in 2018 and 2017 was $3,836,536 and $2,562,473, respectively.

For the years ended December 31, 2019, 2018 and 2017, 247,855 shares, 698,019 shares, and 910,105 shares, respectively, related to stock option plans were not included in diluted average common shares outstanding because they were anti-dilutive.

Other Comprehensive Income (Loss)

Comprehensive income (loss) 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, derivatives, and foreign currency translation adjustments that are further detailed in Note 9 to the Consolidated Financial Statements.

Foreign Currency Translation

The financial position and results of operations of the Company’s foreign subsidiaries are measured using the local currency as the functional currency. Assets and liabilities are translated at the exchange rate in effect at year-end. Income statement accounts are translated at the average rate of exchange in effect during the year. The resulting translation adjustment is recorded as a separate component of shareholders’ investment. Gains and losses arising from re-measuring foreign currency transactions into the appropriate currency are included in the determination of net income.

Stock-Based Compensation Plans

The Company accounts for stock-based compensation using the fair value recognition provisions of ASC 718, Compensation - Stock Compensation. As described more fully in Note 5, the Company provides compensation benefits under an omnibus incentive plan, two other stock option plans, another restricted stock plan, and an employee stock purchase plan. The Company utilizes the Black-Scholes model, which requires the input of subjective assumptions. These assumptions include estimating (a) the length of time employees will retain their vested stock options before exercising them (“expected term”), (b) the volatility of the Company’s common stock price over the expected term, (c) the number of options that will ultimately not complete their vesting requirements (“forfeitures”) and (d) expected dividends. Changes in the subjective assumptions can materially affect the estimate of fair value of stock-based compensation and consequently, the related amounts recognized on the consolidated condensed statements of operations.

Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Recent Accounting Standards

Effective January 1, 2019, the Company adopted Accounting Standards Update ("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 ("ROU") asset and a lease liability for substantially all leases (other than leases that meet the definition of a short-term lease). The liability will be equal to the present value of lease payments. Treatment in the consolidated statements of income will be similar to the historical treatment of operating and capital leases. The adoption of this standard did not have a material impact on the Company's consolidated balance sheet or consolidated income statement. Disclosures are now required to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases.

Effective January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments. The standard requires a change in the measurement approach for credit losses on financial assets measured on an amortized cost basis from an incurred loss method to an expected loss method, thereby eliminating the requirement that a credit loss be

considered probable to impact the valuation of a financial asset measured on an amortized cost basis. The standard requires the measurement of expected credit losses to be based on relevant information about past events, including historical experience, current conditions, and a reasonable and supportable forecast that affects the collectability of the related financial asset. It also modifies the impairment model for available-for-sale debt securities and provides a simplified accounting model for purchased financial assets with credit deterioration since their origination. The adoption of this standard will not have a material impact on the Company's consolidated balance sheet or consolidated income statement.

Debt and Financing Arrangements	12 Months Ended
Debt and Financing Arrangements	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt and Financing Arrangements	DEBT AND FINANCING ARRANGEMENTS On October 15, 2018, the Company entered into a Credit Agreement ("Credit Agreement") with PNC as the administrative agent and sole lender. Pursuant to this Credit Agreement, the Company has access to a $150 million senior revolving credit facility (“Revolver”). Under the terms of the Credit Agreement, the Company is entitled to further request an additional aggregate principal amount of up to $100 million, subject to the satisfaction of certain conditions. In addition, the Company is entitled to the benefit of Swing Loans from amounts otherwise available under the Revolver in the aggregate principal amount of up to $20 million and to request Letters of Credit from amounts otherwise available under the Revolver in the aggregate principle amount up to $20 million, both subject to certain conditions. The obligations of the Company under the Credit Agreement are not secured, but are subject to certain covenants. As of December 31, 2019 and 2018, there were no outstanding balances on the Revolver. The Revolver expires on October 15, 2023. The Credit Agreement contains customary representations and warranties and certain covenants that place certain limitations on the Company. As of December 31, 2019, the Company was in compliance with its covenants under the Credit Agreement.

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

INCOME TAXES

The provision for income taxes is based on the earnings reported in the accompanying consolidated financial statements. The Company recognizes deferred income tax liabilities and assets for the expected future tax consequences of events that have been included in the consolidated financial statements or tax returns. Under this method, deferred income tax liabilities and assets are determined based on the cumulative temporary differences between the financial statement and tax basis of assets and liabilities using enacted tax rates expected to be applied to taxable income in years which those temporary differences are expected to be recovered or settled. Deferred income tax expense is measured by the net change in deferred income tax assets and liabilities during the year.

The Tax Cuts and Jobs Act (the “Act”), a tax reform bill signed into law in 2017, reduced the current federal income tax rate for corporations to 21% from 35%, among other things. The rate reduction was effective as of January 1, 2018, and as written is permanent. The Act caused the Company’s deferred income taxes to be revalued during calendar year 2017, resulting in a reduction to income tax expense of $38.4 million in that period. As changes in tax laws or rates are enacted, deferred tax assets and liabilities are adjusted through income tax expense. The one time transition tax calculation, a separate provision of the Act, was also competed and was not material.

The foreign components of income before the provision for income taxes were not material for the year ended December 31, 2019, 2018 and 2017. The components of the provision for income taxes are as follows:



	2019			2018			2017
Currently payable:
Federal	$	73,563,685		$	83,010,387		$	133,166,194
State	3,765,929			3,743,781			3,984,000
Foreign	1,468,018			1,776,837			2,440,000
Total	78,797,632			88,531,005			139,590,194
Deferred income tax (benefit) expense:
Primarily federal	(3,066,237		)	(4,367,155		)	(14,585,412		)
Provision for income taxes	$	75,731,395		$	84,163,850		$	125,004,782

The effective income tax rates are different from the statutory federal income tax rates for the following reasons:



	2019		2018		2017
Statutory federal income tax rate	21.0	%	21.0	%	35.0	%
State income taxes, net of federal income tax benefit	0.6		0.6		0.5
Domestic production exclusion	—		—		(2.8	)
Research tax credit	(1.1	)	(0.8	)	(0.8	)
Increase in reserve for uncertain tax provisions	0.3		0.1		0.1
Change in tax rate on deferred taxes	—		0.5		(7.2	)
Foreign tax credit	(0.1	)	(0.1	)	(0.8	)
Foreign derived intangible income deduction	(4.8	)	(4.6	)	—
Stock compensation	(1.1	)	(1.0	)	(1.0	)
Other	0.3		0.4		0.5
Effective income tax rate	15.1	%	16.1	%	23.5	%

The tax effect of temporary differences which give rise to deferred income tax assets and liabilities at December 31, 2019 and 2018, are as follows:



	December 31,
	2019			2018
Assets:
Accruals not currently deductible	$	6,478,146		$	5,111,242
Stock based compensation	9,100,745			9,586,372
Other	66,830			356,039
Total deferred income tax assets	$	15,645,721		$	15,053,653
Liabilities:
Excess tax over book depreciation	(30,725,471		)	(39,835,025		)
Goodwill	(27,799,640		)	(23,341,226		)
Intangible assets	(6,171,628		)	(5,089,042		)
Other	(2,403,131		)	(1,309,849		)
Total deferred income tax liability	$	(67,099,870	)	$	(69,575,142	)
Net deferred income taxes	$	(51,454,149	)	$	(54,521,489	)

Income taxes paid in cash were approximately $74.9 million, $86.9 million and $126.0 million in 2019, 2018 and 2017, respectively.

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:



	2019			2018			2017
Beginning of year	$	4,678,000		$	4,435,000		$	3,408,000
Additions based on tax positions related to the current year	1,695,000			1,677,000			941,000
Additions for tax positions in prior years	657,000			283,000			289,000
Reductions for tax positions in prior years	(38,000		)	(163,000		)	(63,000		)
Reductions as a result of completed audit examinations	—			(1,554,000		)	—
Reductions as a result of a lapse of the applicable statute of limitations	(600,000		)	—			(140,000		)
End of year	$	6,392,000		$	4,678,000		$	4,435,000

If recognized, unrecognized tax benefits would affect the effective tax rate.

The Company recognizes interest and penalties related to unrecognized tax benefits through the provision for income taxes. The Company has accrued approximately $574,000, $315,000, and $433,000 for interest as of December 31, 2019, 2018, and 2017, respectively. Interest recorded during 2019, 2018 and 2017 was not considered significant.

The Company is also subject to periodic and routine audits in both domestic and foreign tax jurisdictions, and it is reasonably possible that the amounts of unrecognized tax benefits could change as a result of an audit.

Based on the current audits in process, the payment of taxes as a result of audit settlements, and the completion of tax examinations, the Company does not expect these to have a material impact on the Company’s financial position or results of operations.

For the majority of tax jurisdictions, the Company is no longer subject to U.S. federal, state and local, or non-U.S. income tax examinations by tax authorities for years before 2015.

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2019
Retirement Benefits [Abstract]
Employee Benefit Plan	EMPLOYEE BENEFIT PLAN The Company has a 401(k) retirement savings plan in which substantially all of its employees may participate. The plan includes a provision for the Company to match a percentage of the employee’s contributions at a rate determined by the Company’s Board of Directors. In 2019, 2018 and 2017 the Company’s contributions were approximately $8.7 million, $8.2 million and $7.7 million, respectively. The increase in each of the years was due to increased employee participation in the plan. The Company does not provide health care benefits to retired employees. The Gentex Corporation Non-Qualified Deferred Compensation Plan (the "Deferred Compensation Plan") is intended to enhance retirement savings among a select group of management or highly compensated employees who contribute significantly to the success of the Company. It is also intended to constitute an unfunded non-qualified deferred compensation plan described in Sections 201(2), 301(a)(3), and 401(a)(1) of the Employee Retirement Income Security Act of 1974, as amended ("ERISA"). Only select management and highly compensated employees, including executive officers, are eligible to participate. The Deferred Compensation Plan is administered by a committee who shall approve designation of any participants and may also remove participants. Participants may elect, on a pre-tax basis, to defer receipt of compensation by making an election in accordance with the terms of the Deferred Compensation Plan. Participants are immediately vested in their own deferrals and related earnings. The Company may, but is not required, to match participant deferrals. Participants are generally vested in any such matching contributions 50% after two years but before three years of service and 100% after three years of service. A participant's vested credit balance under the Deferred Compensation Plan will generally be paid on the earliest to occur of: a separation from service; a fixed date or event; a change of control; or a plan termination. A participant can elect whether to receive his or her vested credit balance in a lump sum on the relevant payment date or in installments thereafter.

Stock-Based Compensation Plans

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation Plans

STOCK-BASED COMPENSATION PLANS

At December 31, 2019, the Company had two equity incentive plans under which awards are made, which include the Gentex Corporation 2019 Omnibus Incentive Plan ("2019 Omnibus Plan"), and an employee stock purchase plan. Those plans and any material amendments thereto have previously been approved by shareholders.

The 2019 Omnibus Plan provides for the potential awards to: i) employees; and ii) non-employee directors of the Company or its subsidiaries, which potential awards may be stock options, both incentive stock options and non-qualified stock options, appreciation rights, restricted stock, restricted stock units, performance share awards and performance units, and other awards that are stock-based, cash-based or a combination of both. The 2019 Omnibus Plan replaced the Company's Employee Stock Option Plan, Second Restricted Stock Plan, and Amended and Restated Non-Employee Director Stock Option Plan (the "Prior Plans"), which were also approved by shareholders. Any existing awards previously granted under the Prior Plans remain outstanding in accordance with their terms and are governed by the Prior Plans as applicable.

2019 Omnibus Incentive Plan

The 2019 Omnibus Plan covers 45,000,000 shares of common stock. The purpose of the 2019 Omnibus Plan is to attract and retain employees, officers, and directors of the Company and its subsidiaries and to motivate and provide such persons incentives and rewards for performance. As of December 31, 2019, 4,919,256 shares (net of shares from canceled/expired options) have been issued under the 2019 Omnibus Plan, which includes stock options (at a set conversion rate), restricted shares, and performance share awards.

Employee Stock Options

The Employee Stock Option Plan allowed the Company to grant up to 24,000,000 shares of common stock under the plan, prior to its replacement by the 2019 Omnibus Plan.

The Company has granted options on 796,635 shares (net of shares from canceled/expired options) under the 2019 Omnibus Plan and 12,903,592 shares (net of shares from canceled/expired options) under the prior plan through December 31, 2019. Under each of such plans, the option exercise price equals the stock’s market price on date of grant. The options vest after one to five years, and expire after five to ten years.

The fair value of each option grant was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions for the indicated periods:



	2019			2018			2017
Dividend yield⁽¹⁾	2.0		%	2.1		%	2.1		%
Expected volatility ⁽²⁾	23.9		%	26.0		%	26.7		%
Risk-free interest rate ⁽³⁾	1.8		%	2.7		%	2.0		%
Expected term of options (in years) ⁽⁴⁾	4.2			4.2			4.2
Weighted-average grant-date fair value	$	4		$	5		$	4

(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.

As of December 31, 2019, there was $6,316,567 of unrecognized compensation cost related to stock option awards which is expected to be recognized over the remaining vesting periods, with a weighted-average period of 1.90 years.

A summary of the status of the Company’s employee stock option plan at December 31, 2019, 2018 and 2017, and changes during the same periods are presented in the tables below.



	2019
	Shares (000)		Wtd. Avg. Ex. Price		Wtd. Avg. Remaining Contract Life	Aggregate Intrinsic Value (000)
Outstanding at Beginning of Year	8,944		$	18
Granted	1,049		25
Exercised	(4,402	)	16			$	36,294
Forfeited	(156	)	20
Outstanding at End of Year	5,435		20		3.1 Yrs	$	47,170
Exercisable at End of Year	1,859		$	18	2.2 Yrs	$	20,484



	2018
	Shares (000)		Wtd. Avg. Ex. Price		Wtd. Avg. Remaining Contract Life	Aggregate Intrinsic Value (000)
Outstanding at Beginning of Year	11,837		$	16
Granted	1,613		22
Exercised	(4,278	)	15			$	38,097
Forfeited	(228	)	18
Outstanding at End of Year	8,944		18		2.8 Yrs	$	24,881
Exercisable at End of Year	4,101		$	16	1.7 Yrs	$	16,162



	2017
	Shares (000)		Wtd. Avg. Ex. Price		Wtd. Avg. Remaining Contract Life	Aggregate Intrinsic Value (000)
Outstanding at Beginning of Year	14,252		$	15
Granted	1,295		20
Exercised	(3,476	)	13			$	25,156
Forfeited	(234	)	16
Outstanding at End of Year	11,837		16		2.7 Yrs	$	58,202
Exercisable at End of Year	5,297		$	15	2 Yrs	$	32,152

A summary of the status of the Company’s non-vested employee stock option activity for the years ended December 31, 2019, 2018, and 2017, are presented in the table below:



	2019				2018				2017
	Shares (000)		Wtd. Avg Grant Date Fair Value		Shares (000)		Wtd. Avg Grant Date Fair Value		Shares (000)		Wtd. Avg Grant Date Fair Value
Nonvested Stock Options at Beginning of Year	4,842		$	4	6,540		$	4	9,397		$	4
Granted	1,049		4		1,613		5		1,295		4
Vested	(2,165	)	4		(3,089	)	4		(3,941	)	4
Forfeited	(151	)	4		(222	)	4		(211	)	4
Nonvested Stock Options at End of Year	3,575		$	4	4,842		$	4	6,540		$	4

Restricted Shares

The Company’s Second Restricted Stock Plan provided for a maximum number of shares that may be subject to awards of 9,000,000 shares, prior to its replacement by the 2019 Omnibus Plan.

Restricted shares awarded under either that plan or the 2019 Omnibus 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 a committee, appointed by the Board of Directors, but may not exceed ten years. The Company has issued 854,633 shares under the 2019 Omnibus Plan and 5,762,672 shares under the prior plan as of December 31, 2019, and has 3,315,482 shares outstanding under such plans.



	2019			2018			2017
Vesting Period⁽¹⁾	Shares Granted	Market Price at Vesting Date		Shares Granted	Market Price at Vesting Date		Shares Granted	Market Price at Vesting Date
1 Year	39,627	$	22.19	—	$	—	—	$	—
3 Years	64,718	20.40		—	—		—	—
4 Years	773,698	20.68 - 28.98		762,749	20.21 - 23.14		628,015	18.97 - 21.33
5 Years	254,988	20.68 - 28.98		279,420	20.21 - 23.14		228,630	18.97 - 21.33
	1,133,031	$20.40 - 28.98		1,042,169	$20.21 - 23.14		856,645	$18.97 - 21.33
(1) Each of these awards cliff vest after the restriction period with no additional restrictions.

As of December 31, 2019, there was unearned stock-based compensation of $47,139,370 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 of restricted stock for the years ended December 31, 2019, 2018 and 2017 was $13,770,917, $8,841,985, and $5,353,339 respectively.

Performance Shares

Performance shares awarded under the 2019 Omnibus Plan are considered performance condition awards as attainment is based on the Company's performance relative to pre-established metrics. The fair value of such performance share awards was determined using the Company's closing stock price on the date of grant. The expected attainment of the metrics for these awards is then analyzed each reporting period, and the related expense is adjusted based on expected attainment, if the then expected attainment differs from previous expectations. The cumulative effect on current and prior periods of a change in expected attainment is recognized in the period of change. As of December 31, 2019, the Company had unearned stock-based compensation of $2,224,328 associated with these performance share grants. The unearned stock-based compensation related to these grants is being amortized to compensation expense over the applicable performance periods. Amortization expense from performance share grants for the year ended December 31, 2019 was $897,136. No amortization expense for performance share grants was incurred in 2018 or 2017, as no such awards were issued or outstanding.

Employee Stock Purchase Plan

In 2013, the Gentex Corporation Employee Stock Purchase Plan covering 2,000,000 shares of common stock was approved by the shareholders, replacing a prior plan. Under such plan, the Company sells shares at 85% of the stock’s market price at the date of purchase. Under ASC 718, the 15% discounted value is recognized as compensation expense. The following table summarizes shares sold to employees under the 2013 Plan in the years ended December 31, 2019, 2018 and 2017:



Plan	2019	2018	2017	Cumulative Shares Issued in 2019	Weighted Average Fair Value 2019
2013 Employee Stock Purchase Plan	173,013	177,846	175,479	1,145,856	$	21.40

Contingencies	12 Months Ended
Contingencies	Dec. 31, 2019
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 there are matters that constitute material pending legal proceedings that will have a material adverse effect on the financial position, future results of operations, or cash flows of the Company.

Segment Reporting

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Segment Reporting

SEGMENT REPORTING

ASC 280, Segment Reporting, requires that a public enterprise report financial and descriptive information about its reportable operating segments subject to certain aggregation criteria and quantitative thresholds. Operating segments are defined by ASC 280 as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision-makers in deciding how to allocate resources and in assessing performance.



	2019		2018		2017
Revenue:
Automotive Products
United States	$	569,939,756	$	583,672,971	$	567,492,812
Germany	296,276,971		333,002,878		351,123,204
Japan	225,577,146		209,311,790		185,261,067
Mexico	160,967,900		106,111,515		93,603,796
Other Countries	557,775,114		559,099,142		560,646,589
Other	48,360,519		42,865,401		36,745,110
Total	$	1,858,897,406	$	1,834,063,697	$	1,794,872,578
Income (Loss) from Operations:
Automotive Products	$	473,546,112	$	495,471,799	$	512,895,699
Other	14,991,492		12,653,748		10,462,653
Total	$	488,537,604	$	508,125,547	$	523,358,352
Assets:
Automotive Products	$	1,463,030,286	$	1,449,910,935	$	1,472,061,650
Other	16,000,669		14,333,098		9,576,514
Corporate	689,772,238		621,190,035		870,415,748
Total	$	2,168,803,193	$	2,085,434,068	$	2,352,053,912
Depreciation & Amortization:
Automotive Products	$	97,520,972	$	97,279,052	$	95,378,100
Other	481,861		422,844		300,935
Corporate	6,700,141		4,484,918		3,891,873
Total	$	104,702,974	$	102,186,814	$	99,570,908
Capital Expenditures:
Automotive Products	$	63,537,512	$	84,337,455	$	82,703,576
Other	1,704,045		1,447,494		170,357
Corporate	19,338,698		205,621		21,166,986
Total	$	84,580,255	$	85,990,570	$	104,040,919

Other includes Dimmable Aircraft Windows and Fire Protection Products. Major product line revenues included within these segments are as follows:



	2019		2018		2017
Automotive Products
Automotive Mirrors	$	1,638,600,272	$	1,598,589,777	$	1,573,222,820
HomeLink^® Modules*	171,936,615		192,608,519		184,904,648
Total Automotive Products	$	1,810,536,887	$	1,791,198,296	$	1,758,127,468

Other Products Revenue	$	48,360,519	$	42,865,401	$	36,745,110

Total Revenue	$	1,858,897,406	$	1,834,063,697	$	1,794,872,578

*Excludes HomeLink^® revenue integrated into automotive mirrors.

Corporate assets are principally cash and cash equivalents, investments, deferred income taxes and corporate fixed assets. Depreciation & Amortization on corporate fixed assets are allocated as appropriate to the Automotive and Other segments when reviewing operating results. Substantially all long-lived assets are located in the U.S.

Automotive Products revenues in the “Other countries” category are sales to customer automotive manufacturing plants in Korea, Mexico, Canada, Hungary, China, and the United Kingdom as well as other foreign automotive customers. Most of the Company’s non-U.S. sales are invoiced and paid in U.S. dollars. During the years ended December 31, 2019, 2018 and 2017, approximately 7%, 8% and 8% of the Company’s net sales were invoiced and paid in foreign currencies, respectively.

In 2019, the Company had three automotive customers (including direct sales to OEM customers and sales through their Tier 1 suppliers), which individually accounted for 10% or more of net sales as follows:



	Toyota Motor Company		Volkswagen Group		General Motors		Daimler Group		Ford Motor Company
2019	13	%	14	%	11	%	#		#
2018	13	%	15	%	#		10	%	#
2017	12	%	15	%	#		10	%	10	%

# - Less than 10 percent.

Quarterly Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information (Unaudited)

QUARTERLY FINANCIAL INFORMATION (UNAUDITED)

The following table sets forth selected financial information for all of the quarters during the years ended December 31, 2019 and 2018 (in thousands, except per share data):




	First				Second				Third				Fourth
	2019		2018		2019		2018		2019		2018		2019		2018
Net Sales	$	468,589	$	465,420	$	468,711	$	454,981	$	477,761	$	460,253	$	443,836	$	453,409
Gross Profit	169,645		172,628		176,538		172,804		180,321		172,990		161,805		172,044
Operating Income	121,596		128,515		127,905		126,683		128,136		127,428		110,901		125,499
Net Income	104,280		111,249		108,959		109,024		111,898		111,336		99,547		106,275
Earnings Per Share (Basic)⁽¹⁾	$	0.40	$	0.40	$	0.42	$	0.40	$	0.44	$	0.42	$	0.39	$	0.41
Earnings Per Share (Diluted)⁽¹⁾	$	0.40	$	0.40	$	0.42	$	0.40	$	0.44	$	0.42	$	0.39	$	0.41
⁽¹⁾Basic and diluted earnings per share are computed independently for each quarter presented. Therefore the sum of quarterly basic and diluted per share information may not equal annual basis and diluted earnings per share.

Comprehensive Income

12 Months Ended

Dec. 31, 2019

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 unrealized movement in derivative financial instruments designated as hedges.



	For the Twelve Months ended December 31,
	2019			2018			2017
Foreign currency translation adjustments:
Balance at beginning of period	$	(1,674,887	)	$	645,030		$	(2,862,999	)
Other comprehensive (loss) income before reclassifications	(709,702		)	(2,319,917		)	3,508,029
Net current-period change	(709,702		)	(2,319,917		)	3,508,029
Balance at end of period	(2,384,589		)	(1,674,887		)	645,030
Unrealized gains (losses) on available-for-sale securities:
Balance at beginning of period	74,549			6,626,379			2,788,975
ASU 2016-01 adoption impact	—			(6,642,727		)	—
Other comprehensive income before reclassifications	1,403,521			1,675,823			4,444,360
Amounts reclassified from accumulated other comprehensive income	(382,584		)	(1,584,926		)	(606,956		)
Net current-period change	1,020,937			(6,551,830		)	3,837,404
Balance at end of period	1,095,486			74,549			6,626,379
Unrealized gains (losses) on derivatives:
Balance at beginning of period	—			(78,026		)	(1,197,281		)
Other comprehensive income before reclassifications	—			175,308			248,042
Amounts reclassified from accumulated other comprehensive income	—			(97,282		)	871,213
Net current-period change	—			78,026			1,119,255
Balance at end of period	—			—			(78,026		)

Accumulated other comprehensive (loss) income, end of period	$	(1,289,103	)	$	(1,600,338	)	$	7,193,383

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 twelve months ended December 31, 2019, 2018 and 2017.



Details about Accumulated Other Comprehensive Income Components										Affected Line item in the Statement of Consolidated Income
	For the Twelve Months ended December 31,
	2019			2018			2017
Unrealized gains on available-for-sale debt securities
Realized gain on sale of securities	$	484,283		$	2,006,235		$	933,778		Other income (expense), net
Provision for income taxes	(101,699		)	(421,309		)	(326,822		)	Provision for Income Taxes
Total reclassifications for the period	$	382,584		$	1,584,926		$	606,956		Net of tax

Unrealized gains (losses) on derivatives
Realized loss on interest rate swap	$	—		$	123,142		$	(1,340,329	)	Other income (expense), net
Provision for income taxes	—			(25,860		)	469,116			Provision for Income Taxes
	$	—		$	97,282		$	(871,213	)	Net of tax

Total reclassifications for the period	$	382,584		$	1,682,208		$	(264,257	)	Net of tax

Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets

GOODWILL AND INTANGIBLE ASSETS

The Company recorded Goodwill of $307.4 million related to the HomeLink^® acquisition, which occurred in September 2013. The carrying value of Goodwill as of both December 31, 2019 and December 31, 2018 was $307.4 million as set forth in the table below.



	Carrying Amount
Balance as of December 31, 2018	$	307,365,845
Acquisitions	—
Divestitures	—
Impairments	—
Other	—
Balance as of December 31, 2019	$	307,365,845

The Company reviews goodwill for impairment during the fourth quarter on an annual basis or more frequently if events or changes in circumstances indicate that goodwill might be impaired. The Company has not recognized any impairment of goodwill in the current or prior periods. 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 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 macro-economic conditions. No such events or circumstances that negatively impacted the key assumptions were noted in 2019.

The Intangible Assets and related change in carrying values are set forth in the table below as of December 31, 2019 and December 31, 2018.

As of December 31, 2019:



Other Intangible Assets	Gross		Accumulated Amortization			Net		Assumed Useful Life
HomeLink^®Trade Names and Trademarks	$	52,000,000	$	—		$	52,000,000	Indefinite
HomeLink^®Technology	180,000,000		(93,750,000		)	$	86,250,000	12 years
Existing Customer Platforms	43,000,000		(26,875,000		)	$	16,125,000	10 years
Exclusive Licensing Agreement	96,000,000		—			$	96,000,000	Indefinite
Total other identifiable intangible assets	371,000,000		(120,625,000		)	250,375,000

As of December 31, 2018:



Other Intangible Assets	Gross		Accumulated Amortization			Net		Assumed Useful Life
HomeLink^®Trade Names and Trademarks	$	52,000,000	$	—		$	52,000,000	Indefinite
HomeLink^®Technology	180,000,000		(78,750,000		)	$	101,250,000	12 years
Existing Customer Platforms	43,000,000		(22,575,000		)	$	20,425,000	10 years
Exclusive Licensing Agreement	96,000,000		—			$	96,000,000	Indefinite
Total other identifiable intangible assets	371,000,000		(101,325,000		)	269,675,000

Accumulated amortization on patents and intangible assets was approximately $143.1 million and $122.3 million at December 31, 2019 and 2018, respectively. Amortization expense on patents and other intangible assets was approximately $22.4 million, $22.5 million, and $22.5 million in calendar years 2019, 2018 and 2017, respectively. At December 31, 2019, patents had a weighted average amortized life of 10 years.

Excluding the impact of any future acquisitions, the Company anticipates amortization expense including patents and other intangible assets for each of the years ended December 31, 2020 and 2021 to be approximately $22 million annually, approximately $21 million for the year ended December 31, 2022, approximately $19 million for the year ended December 31, 2023, and approximately $16 million for the year ended December 31, 2024.

Revenue

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Revenue

REVENUE

The following table shows the Company’s Automotive and Other Products revenue disaggregated by geographical location for Automotive Products for the twelve month periods ended December 31, 2019, 2018, and 2017:



	For the Twelve Months ended December 31,
Revenue	2019		2018		2017
Automotive Products
U.S.	$	569,939,756	$	583,672,971	$	567,492,812
Germany	296,276,971		333,002,878		351,123,204
Japan	225,577,146		209,311,790		185,261,067
Mexico	160,967,900		106,111,515		93,603,796
Other	557,775,114		559,099,142		560,646,589
Total Automotive Products	$	1,810,536,887	$	1,791,198,296	$	1,758,127,468
Other Products (U.S.)	48,360,519		42,865,401		36,745,110
Total Revenue	$	1,858,897,406	$	1,834,063,697	$	1,794,872,578

Revenue by geographic area may fluctuate based on many factors, including: exposure to local economic, political and labor conditions; unexpected changes in laws, regulations, trade or monetary or fiscal policy, including interest rates, foreign currency exchange rates and changes in the rate of inflation in the U.S. and other foreign countries; and tariffs, quotas, customs and other import or export restrictions and other trade barriers.

The following table disaggregates the Company’s Automotive and Other revenue by major source for the twelve month periods ended December 31, 2019 and 2018:



	For the Twelve Months Ended December 31,
Revenue	2019		2018
Automotive Segment
Automotive Mirrors & Electronics	$	1,638,600,272	$	1,598,589,777
HomeLink Modules*	171,936,615		192,608,519
Total Automotive Products	$	1,810,536,887	$	1,791,198,296

Other Segment
Fire Protection Products	$	23,740,261	$	22,109,784
Windows Products	24,620,258		20,755,617
Total Other	$	48,360,519	$	42,865,401

*Excludes HomeLink revenue related to HomeLink modules integrated into automotive mirrors.

Revenue is recognized when obligations under the terms of a contract with the customer are satisfied. Such recognition generally occurs with the transfer of control of the products at a point in time. The Company's automotive OEM contracts generally include Long Term Supply Agreements ("LTSA") entered into in the ordinary course of business and Purchase Orders ("PO") whereby the LTSA sometimes stipulates the pricing and delivery terms and is evaluated together with a PO, which identifies the quantity, timing, and the type of product to be transferred. Certain customer contracts do not always have an LTSA, in which case, the contracts are governed by the PO from the customer in conjunction with other mutually agreed upon terms and conditions.

The Company does not generate revenue from arrangements with multiple deliverables. Revenue is measured as the amount of consideration the Company expects to receive in exchange for transferring goods excluding revenue amounts that are transferred to third parties, such as sales, value add, and other taxes the Company collects concurrently with revenue-producing activities. The Company does not incur any incremental cost to obtain contracts. Costs are incurred to fulfill contracts with the OEM. However, such costs are accounted for under ASC 340-10, and are not treated as fulfillment costs under ASC 340-40.

Automotive Products Segment

Automotive Rearview Mirrors and Electronics

The Company manufactures interior electrochromic automatic-dimming rearview mirrors that darken to reduce glare and improve visibility for the driver. These electronic interior mirrors can also include additional electronic features such as compass, microphones, HomeLink^®, lighting assist and driver assist forward safety camera systems, various lighting systems, various telematics systems, ITM^® systems, and a wide variety of displays. The Company also ships interior non-automatic-dimming rearview mirrors with features. The Company’s interior electrochromic automatic-dimming rearview mirrors also power the application of the Company’s exterior electrochromic automatic-dimming rearview mirrors that darken to reduce glare and improve visibility for the driver. These electronic exterior mirrors typically range in size and shape per automaker specification, but also include additional features such as turn signal indicators, side blind zone indicators, and courtesy lighting. The Company also ships exterior non-automatic-dimming rearview mirrors with similar electronic features as what is available in its automatic-dimming applications. The Company manufactures other automotive electronics products both inside and outside of the rearview mirror through HomeLink^®applications in the vehicle including the rearview mirror, interior visor, overhead console, or center console.

For the majority of automotive products, transfer of control and revenue recognition occurs when the Company ships the product from the manufacturing facility to the customer. The Company generally receives payment equal to the price that applies at the time of invoice for most automotive product sales. For any shipments of product that may be subject to retroactive price adjustments that are then being negotiated, the Company records revenue based on the Company’s best estimate of the amount of consideration to which the entity will be entitled in exchange for transferring the promised goods to the customer. The Company's best estimate requires significant judgment based on historical results and expected outcomes of ongoing negotiations with customers. The Company's approach is to consider these adjustments to the contract price as variable consideration which is estimated based on the then most likely price amount. Payment terms on automotive part sales to customers range from 15 days to 90 days. Estimated revenue is adjusted at the earlier of when the most likely amount of consideration expected to be received changes or when the consideration becomes fixed.

HomeLink^® Modules

The Company manufactures and sells HomeLink® Modules individually, as well as in combination with the automotive mirrors and other advanced features, as described above. For the majority of automotive products, transfer of control and revenue recognition occurs when the Company ships the product from the manufacturing facility to the customer.

Other Segment

Dimmable Aircraft Windows

The Company supplies variable dimmable windows for the passenger compartment on the Boeing 787 Dreamliner Series of Aircraft. For dimmable aircraft windows, transfer of control and revenue recognition occurs when the Company ships the product from the manufacturing facility to the customer. Payment terms on dimmable aircraft window sales range from 30 days to 45 days.

Fire Protection Products

The Company manufactures photoelectric smoke detectors and alarms, visual signaling alarms, electrochemical carbon monoxide detectors and alarms, audible and visual signaling alarms, and bells and speakers for use in fire detection systems in office buildings, hotels, and other commercial and residential buildings. For fire protection parts, transfer of control and revenue recognition occurs when the Company ships the product from the manufacturing facility to the customer. Payment terms on fire protection part sales to customers range from 30 days to 75 days.

Summary of Significant Accounting and Reporting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Consolidation	Consolidation The consolidated financial statements include the accounts of Gentex Corporation and all of its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated.
Cash Equivalents	Cash Equivalents Cash equivalents consist of funds invested in bank accounts and money market funds that have daily liquidity.
Allowance For Doubtful Accounts	Allowance For Doubtful Accounts The Company reviews a monthly aging report of all accounts receivable balances starting with invoices outstanding over sixty days. In addition, the Company monitors information about its customers through a variety of sources including the media, and information obtained through on-going interaction between Company personnel and the customer. Based on the evaluation of the above information, the Company estimates its allowances related to customer receivables on historical credit and collections experience, customers current financial condition and the specific identification of other potential problems, including the economic climate. Actual collections can differ, requiring adjustments to the allowances, but historically such adjustments have not been material The Company’s allowance for doubtful accounts primarily relates to financially distressed automotive customers. The Company continues to work with these financially distressed customers in collecting past due balances.
Investments	ASC 320, Accounting for Certain Investments in Debt and Equity Securities, as amended and interpreted, provides guidance on determining when an investment is other-than-temporarily impaired. The Company reviews its fixed income investments 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 new cost basis in the investment is established. If market, industry, and/or investee conditions deteriorate, the Company may incur future impairments. Investments The Company follows the provisions of ASC 820, Fair Value Measurements and Disclosures, for its financial assets and liabilities, and for its non-financial assets and liabilities subject to fair value measurements. ASC 820 provides a framework for measuring the fair value of assets and liabilities. This framework is intended to provide increased consistency in how fair value determinations are made under various existing accounting standards that permit, or in some cases, require estimates of fair-market value. This standard also expanded financial statement disclosure requirements about a company’s use of fair-value measurements, including the effect of such measurement on earnings. The cost of securities sold is based on the specific identification method. The Company determines the fair value of its government securities, asset-backed securities, corporate bonds, and certain mutual funds by utilizing monthly valuation statements that are provided by its broker. The broker determines the investment valuation by utilizing the bid price in the market and also refers to third party sources to validate valuations, and as such are classified as Level 2 assets. The Company's certificates of deposit are classified as available for sale, and are considered as Level 1 assets. These investments are carried at cost, which approximates fair value. The Company will also periodically make technology investments in certain non-consolidated third-parties. These equity investments are accounted for in accordance with ASC 321, Investments - Equity Securities. Equity investments that do not have readily determinable fair values, and where the Company has not identified any observable events that would cause adjustment of the valuation to date, are held at cost. These technology investments totaled $9.0 million and $3.9 million as of December 31, 2019 and December 31, 2018, respectively. These investments are classified within Long-Term Investments in the consolidated balance sheet and are not included within the tables below.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial instruments consist of cash and cash equivalents, investments, accounts receivable, accounts payable, and short and long-term debt. The Company’s estimate of the fair values of these financial instruments approximates their carrying amounts at December 31, 2019 and 2018.
Inventories	Estimated inventory allowances for slow-moving and obsolete inventories are based on current assessments of future demands, market conditions, evaluation of longer lead times for certain electronic components and related management initiatives. If market conditions or customer requirements change and are less favorable than those projected by management, inventory allowances are adjusted accordingly. Inventories Inventories include material, direct labor and manufacturing overhead and are valued at the lower of first-in, first-out (FIFO) cost or net realizable value.
Plant and Equipment	Plant and Equipment Plant and equipment is stated at cost. Depreciation and amortization are computed for financial reporting purposes using the straight-line method, with estimated useful lives of 7 to 30 years for buildings and improvements, and 3 to 10 years for machinery and equipment.
Impairment or Disposal of Long-Lived Assets	Impairment or Disposal of Long-Lived Assets The Company reviews long-lived assets, including property, plant and equipment and other intangible assets with definite lives, for impairment whenever events or changes in circumstances indicate that the asset’s carrying amount may not be recoverable. The Company conducts its long-lived asset impairment analysis in accordance with ASC 360-10-15, Impairment or Disposal of Long-Lived Assets. ASC 360-10-15 requires the Company to group assets and liabilities at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities and evaluate the asset group against the sum of the undiscounted future cash flows. If the undiscounted cash flows do not indicate the carrying amount of the asset is recoverable, an impairment charge is measured as the amount by which the carrying amount of the asset group exceeds its fair value based on discounted cash flow analysis or appraisals.
Patents	Patents The Company’s policy is to capitalize costs incurred to obtain patents. The cost of patents is amortized over their useful lives. The cost of patents in process is not amortized until issuance. The Company periodically obtains intellectual property rights, in the ordinary course of business, and the cost of the rights are amortized over their useful lives.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill reflects the cost of an acquisition in excess of the fair values assigned to identifiable net assets acquired. The Company reviews goodwill for impairment during the fourth quarter on an annual basis or more frequently if events or changes in circumstances indicate that goodwill might be impaired. The Company performs an impairment review for its automotive reporting unit, which has been determined to be one of the Company’s reportable segments, using either a qualitative approach or quantitative approach which utilizes a fair value method that incorporates certain assumptions and judgments. The fair value of a reporting unit refers to the price that would be received to sell the unit as a whole in an orderly transaction between market participants at the measurement date. The Company performs a qualitative assessment (step 0) to determine whether it is more likely than not that a reporting unit's fair value is less than its carrying amount. If not, no further goodwill impairment testing is performed. If so, we determine the fair value of the reporting unit using step 1 and step 2 tests. If the fair value of the reporting unit is greater than its carrying amount, goodwill is not considered to be impaired. However, if the fair value of the reporting unit is less than its carrying amount, an impairment change is recorded as the excess of the reporting units carrying value over its fair value. The assumptions included in the impairment tests require judgment and changes to these inputs could impact the results of the calculations which could result in an impairment charge in future periods if the carrying amount of the reporting unit exceeds its calculated fair value. For the qualitative assessment performed, management considers factors such as macro-economic conditions, industry and market considerations, overall financial performance, and other company-specific events, amongst other factors, in making the determination as to whether it is more likely than not that a reporting unit's fair value is less than its carrying amount. Other than management's internal projections of future cash flows, the primary assumptions used in the step 1 and step 2 impairment tests are the weighted-average cost of capital and long-term growth rates. Although the Company's cash flow forecasts are based on assumptions that are considered reasonable by management and consistent with the plans and estimates management is using to operate the underlying business, there are significant judgments in determining the expected future cash flows attributable to a reporting unit. There have been no impairment charges recorded currently or in prior periods in which goodwill existed. Indefinite lived intangible assets are also subject to annual impairment testing or more frequently if indicators of impairment are identified. Management judgment and assumptions are required in determining the underlying fair value of the indefinite lived intangible assets. While the Company believes the judgments and assumptions used in determining fair value are reasonable, different assumptions could change the estimated fair values and, therefore, impairment charges could be required, which could be material to the consolidated financial statements. The indefinite lived intangible assets were not impaired as a result of the annual test prepared by management for either period presented.
Revenue Recognition	Revenue Recognition The Company recognizes revenue in accordance with Accounting Standards Codification (ASC) 606, Revenue from Contracts with Customers. Accordingly, revenue is recognized in an amount that reflects the consideration to which the Company expects to be entitled in exchange for promised goods or services when it transfers those goods or services to customers. Sales are shown net of returns, which have not historically been significant. The Company does not generate sales from arrangements with multiple deliverables. The Company generally receives purchase orders from customers on an annual basis. Typically, such purchase order provide the annual terms, including pricing, related to a particular vehicle model. Purchase orders generally do not specify quantities. The Company recognizes revenue based on the pricing terms included in our annual purchase orders. As part of certain agreements, entered into in the ordinary course of business, the Company is asked to provide customers with annual price reductions. Such amounts are subject to estimate and are accrued as a reduction of revenue as products are shipped to those customers. For any shipments of product that may be subject to retroactive price adjustments that are then being negotiated, the Company records revenue based on the Company’s best estimate of the amount of consideration to which the entity will be entitled in exchange for transferring the promised goods to the customer. The Company's best estimate requires significant judgment based on historical results and expected outcomes of ongoing negotiations with customers. The Company's approach is to consider these adjustments to the contract price as variable consideration which is estimated based on the then most likely price amount. In addition, the Company has ongoing adjustments to our pricing arrangements with customers based on the related content, the cost of our products and other commercial factors. Such pricing accruals are adjusted as they are settled with our customers.
Advertising and Promotional Materials	Advertising and Promotional Materials All advertising and promotional costs are expensed as incurred
Repairs and Maintenance	Repairs and Maintenance Major renewals and improvements of property and equipment are capitalized, and repairs and maintenance are expensed as incurred.
Self-Insurance	Self-Insurance The Company is self-insured for a portion of its risk on workers’ compensation and employee medical costs. The arrangements provide for stop loss insurance to manage the Company’s risk. Such costs are accrued based on known claims and an estimate of incurred, but not reported (IBNR) claims. IBNR claims are estimated using historical lag information and other data provided by claims administrators. This estimation process is subjective, and to the extent that future results differ from original estimates, adjustments to recorded accruals may be necessary.
Product Warranty	Product Warranty The Company periodically incurs product warranty costs. Any liabilities associated with product warranty are estimated based on known facts and circumstances and are not significant at December 31, 2019, 2018 and 2017. The Company does not offer extended warranties on its products.
Income Taxes	Income Taxes The provision for income taxes is based on the earnings reported in the consolidated financial statements. Deferred income tax assets and liabilities are computed for differences between the financial statement and tax basis of assets and liabilities that will result in deductible or taxable amounts in the future. Such deferred income tax asset and liability computations are based on enacted tax laws and rates. The Company applies the provisions of ASC 740, Income Taxes, as it relates to uncertainty in income taxes recognized in the Company’s consolidated financial statements. A threshold of more likely than not to be sustained upon examination is applied to uncertain tax positions. The Company deems the estimates related to this provision to be reasonable, however, no assurance can be given that the final outcome of these matters will not vary from what is reflected in the historical income tax provisions and accruals.
Leases	Leases The Company has operating leases for corporate offices, warehouses, vehicles, and other equipment, which are included within "Plant and Equipment" section of the Consolidated Balance Sheets. The leases have remaining lease terms of 1 year to 5 years. The weighted average remaining lease term for operating leases as of December 31, 2019 was 2 years, with a weighted average discount rate of 2.9%.
Earnings Per Share	Earnings Per Share The Company has unvested share-based payment awards with a right to receive non-forfeitable dividends, which are considered participating securities under ASC 260, Earnings Per Share. The Company allocates earnings to participating securities and computes earnings per share using the two-class method. Under the two-class method, net income per share is computed by dividing net income allocated to common shareholders by the weighted average number of common shares outstanding for the period. In applying the two-class method, net income is allocated to both common shares and participating securities based on their respective weighted average shares outstanding for the period.
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Comprehensive income (loss) 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, derivatives, and foreign currency translation adjustments that are further detailed in Note 9 to the Consolidated Financial Statements.
Foreign Currency Translation	Foreign Currency Translation The financial position and results of operations of the Company’s foreign subsidiaries are measured using the local currency as the functional currency. Assets and liabilities are translated at the exchange rate in effect at year-end. Income statement accounts are translated at the average rate of exchange in effect during the year. The resulting translation adjustment is recorded as a separate component of shareholders’ investment. Gains and losses arising from re-measuring foreign currency transactions into the appropriate currency are included in the determination of net income.
Stock-Based Compensation Plans	Stock-Based Compensation Plans The Company accounts for stock-based compensation using the fair value recognition provisions of ASC 718, Compensation - Stock Compensation. As described more fully in Note 5, the Company provides compensation benefits under an omnibus incentive plan, two other stock option plans, another restricted stock plan, and an employee stock purchase plan. The Company utilizes the Black-Scholes model, which requires the input of subjective assumptions. These assumptions include estimating (a) the length of time employees will retain their vested stock options before exercising them (“expected term”), (b) the volatility of the Company’s common stock price over the expected term, (c) the number of options that will ultimately not complete their vesting requirements (“forfeitures”) and (d) expected dividends. Changes in the subjective assumptions can materially affect the estimate of fair value of stock-based compensation and consequently, the related amounts recognized on the consolidated condensed statements of operations.
Estimates	Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Recent Accounting Standards	Recent Accounting Standards Effective January 1, 2019, the Company adopted Accounting Standards Update ("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 ("ROU") asset and a lease liability for substantially all leases (other than leases that meet the definition of a short-term lease). The liability will be equal to the present value of lease payments. Treatment in the consolidated statements of income will be similar to the historical treatment of operating and capital leases. The adoption of this standard did not have a material impact on the Company's consolidated balance sheet or consolidated income statement. Disclosures are now required to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. Effective January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments. The standard requires a change in the measurement approach for credit losses on financial assets measured on an amortized cost basis from an incurred loss method to an expected loss method, thereby eliminating the requirement that a credit loss be considered probable to impact the valuation of a financial asset measured on an amortized cost basis. The standard requires the measurement of expected credit losses to be based on relevant information about past events, including historical experience, current conditions, and a reasonable and supportable forecast that affects the collectability of the related financial asset. It also modifies the impairment model for available-for-sale debt securities and provides a simplified accounting model for purchased financial assets with credit deterioration since their origination. The adoption of this standard will not have a material impact on the Company's consolidated balance sheet or consolidated income statement.

Summary of Significant Accounting and Reporting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Schedule of Allowance For Doubtful Accounts

The following table presents the activity in the Company’s allowance for doubtful accounts:



	Beginning Balance		Net Additions/ (Reductions) to Costs and Expenses		Deductions and Other Adjustments			Ending Balance
Year Ended December 31, 2019:
Allowance for Doubtful Accounts	$	2,746,647	$	—	$	(295,354	)	$	2,451,293
Year Ended December 31, 2018:
Allowance for Doubtful Accounts	$	2,714,533	$	—	$	32,114		$	2,746,647
Year Ended December 31, 2017:
Allowance for Doubtful Accounts	$	2,917,424	$	—	$	(202,891	)	$	2,714,533

Schedule of Assets or Liabilities Having Recurring Measurements

Assets or liabilities that have recurring fair value measurements are shown below as of December 31, 2019 and December 31, 2018:



			Fair Value Measurements at Reporting Date Using
	Total as of		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	December 31, 2019		(Level I)		(Level 2)		(Level 3)
Cash & Cash Equivalents	$	296,321,622	$	296,321,622	$	—	$	—
Short-Term Investments:
Certificate of Deposit	50,099,795		50,099,795		—		—
Corporate Bonds	29,219,685		—		29,219,685		—
Government Securities	58,432,823		—		58,432,823		—
Other	2,631,750		2,631,750		—		—
Long-Term Investments:
Asset-backed Securities	25,791,029		—		25,791,029		—
Certificate of Deposit	3,557,798		3,557,798		—		—
Corporate Bonds	22,815,998		—		22,815,998		—
Government Securities	6,088,190		—		6,088,190		—
Municipal Bonds	72,638,690		—		72,638,690		—
Total	$	567,597,380	$	352,610,965	$	214,986,415	$	—



			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, 2018		(Level I)		(Level 2)		(Level 3)
Cash & Cash Equivalents	217,025,278		$	217,025,278	$	—	$	—
Short-Term Investments:
Certificate of Deposit	150,299,384		150,299,384		—		—
Corporate Bonds	6,967,700		—		6,967,700		—
Government Securities	9,176,227		—		9,176,227		—
Other	2,219,688		2,219,688		—		—
Long-Term Investments:
Corporate Bonds	60,369,930		—		60,369,930		—
Municipal Bonds	18,025,432		—		18,025,432		—
Government Securities	56,483,720		—		56,483,720		—
Total	$	520,567,359	$	369,544,350	$	151,023,009	$	—

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 December 31, 2019 and 2018:



	Unrealized
2019	Cost		Gains		Losses			Market Value
Short-Term Investments:
Certificate of Deposit	$	50,099,795	$	—	$	—		$	50,099,795
Corporate Bonds	29,025,624		194,061		—			29,219,685
Government Securities	58,343,911		99,917		(11,005		)	58,432,823
Other	2,631,750		—		—			2,631,750
Long-Term Investments:
Asset-backed Securities	25,971,156		—		(180,127		)	25,791,029
Certificate of Deposit	3,500,000		58,808		(1,010		)	3,557,798
Corporate Bonds	22,306,130		509,868		—			22,815,998
Government Securities	6,012,705		75,485		—			6,088,190
Municipal Bonds	71,997,996		1,036,116		(395,422		)	72,638,690
Total	$	269,889,067	$	1,974,255	$	(587,564	)	$	271,275,758



	Unrealized
2018	Cost		Gains		Losses			Market Value
Short-Term Investments:
Certificate of Deposit	$	150,299,384	$	—	$	—		$	150,299,384
Government Securities	9,186,586		—		(10,359		)	9,176,227
Corporate Bonds	6,981,305		—		(13,605		)	6,967,700
Other	2,219,688		—		—			2,219,688
Long-Term Investments:
Corporate Bonds	60,659,498		50,340		(339,908		)	60,369,930
Common Stocks	—		—		—			—
Municipal Bonds	17,840,518		184,914		—			18,025,432
Government Securities	56,280,552		205,553		(2,385		)	56,483,720
Total	$	303,467,531	$	440,807	$	(366,257	)	$	303,542,081

Schedule of Unrealized Losses on Investments

Unrealized losses on investments as of December 31, 2019 are as follows:



	Aggregate Unrealized Losses		Aggregate Fair Value
Less than one year	$	587,564	$	90,721,081
Greater than one year	—		—
Total	$	587,564	$	90,721,081

Unrealized losses on investments as of December 31, 2018 are as follows:



	Aggregate Unrealized Losses		Aggregate Fair Value
Less than one year	$	365,824	$	68,722,980
Greater than one year	433		3,000,000
Total	$	366,257	$	71,722,980

Investments Classified by Contractual Maturity Date

Fixed income securities as of December 31, 2019, have contractual maturities as follows:



Due within one year	$	137,752,302
Due between one and five years	43,125,222
Due over five years	87,766,483
	$	268,644,007

Schedule of Inventories

Inventories consisted of the following as of December 31, 2019 and 2018:



	2019		2018
Raw materials	$	164,974,553	$	139,058,541
Work-in-process	33,069,255		35,386,615
Finished goods	50,898,047		50,836,443
Total Inventory	$	248,941,855	$	225,281,599

Schedule of Future Minimum Lease Payments

Future minimum lease payments for operating leases as of December 31, 2019 were as follows:



Year ending December 31,

2020	$	786,807
2021	297,316
2022	145,154
2023	19,296
Thereafter	15,105
Total future minimum lease payments	$	1,263,678
Less imputed interest	(84,964		)
Total	$	1,178,714

Schedule of Earnings Per Share Basic and Diluted

The following table sets forth the computation of basic and diluted net income per common share under the two-class method for each of the last three years:



	2019		2018		2017
Basic Earnings Per Share
Net Income	$	424,683,939	$	437,883,097	$	406,791,922
Less: Allocated to participating securities⁽¹⁾	5,028,813		—		—
Net Income available to common shareholders	$	419,655,126	$	437,883,097	$	406,791,922

Basic weighted average shares outstanding	251,766,382		267,794,786		285,864,997
Net Income per share - Basic	$	1.67	$	1.64	$	1.42

Diluted Earnings Per Share
Allocation of Net Income used in basic computation	$	419,655,126	$	437,883,097	$	406,791,922
Reallocation of undistributed earnings	21,104		21,007		19,398
Net Income available to common shareholders - Diluted	$	419,676,230	$	437,904,104	$	406,811,320

Number of shares used in basic computation	251,766,382		267,794,786		285,864,997
Additional weighted average dilutive common stock equivalents	1,506,608		2,082,563		2,361,092
Diluted weighted average shares outstanding	253,272,990		269,877,349		288,226,089

Net income per share - Diluted	$	1.66	$	1.62	$	1.41

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Components of Provision For Income Taxes

The components of the provision for income taxes are as follows:



	2019			2018			2017
Currently payable:
Federal	$	73,563,685		$	83,010,387		$	133,166,194
State	3,765,929			3,743,781			3,984,000
Foreign	1,468,018			1,776,837			2,440,000
Total	78,797,632			88,531,005			139,590,194
Deferred income tax (benefit) expense:
Primarily federal	(3,066,237		)	(4,367,155		)	(14,585,412		)
Provision for income taxes	$	75,731,395		$	84,163,850		$	125,004,782

Schedule of Effective Income Tax Rates Different From Statutory Federal Income Tax Rates

The effective income tax rates are different from the statutory federal income tax rates for the following reasons:



	2019		2018		2017
Statutory federal income tax rate	21.0	%	21.0	%	35.0	%
State income taxes, net of federal income tax benefit	0.6		0.6		0.5
Domestic production exclusion	—		—		(2.8	)
Research tax credit	(1.1	)	(0.8	)	(0.8	)
Increase in reserve for uncertain tax provisions	0.3		0.1		0.1
Change in tax rate on deferred taxes	—		0.5		(7.2	)
Foreign tax credit	(0.1	)	(0.1	)	(0.8	)
Foreign derived intangible income deduction	(4.8	)	(4.6	)	—
Stock compensation	(1.1	)	(1.0	)	(1.0	)
Other	0.3		0.4		0.5
Effective income tax rate	15.1	%	16.1	%	23.5	%

Schedule of Deferred Income Tax Assets And Liabilities

The tax effect of temporary differences which give rise to deferred income tax assets and liabilities at December 31, 2019 and 2018, are as follows:



	December 31,
	2019			2018
Assets:
Accruals not currently deductible	$	6,478,146		$	5,111,242
Stock based compensation	9,100,745			9,586,372
Other	66,830			356,039
Total deferred income tax assets	$	15,645,721		$	15,053,653
Liabilities:
Excess tax over book depreciation	(30,725,471		)	(39,835,025		)
Goodwill	(27,799,640		)	(23,341,226		)
Intangible assets	(6,171,628		)	(5,089,042		)
Other	(2,403,131		)	(1,309,849		)
Total deferred income tax liability	$	(67,099,870	)	$	(69,575,142	)
Net deferred income taxes	$	(51,454,149	)	$	(54,521,489	)

Schedule of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:



	2019			2018			2017
Beginning of year	$	4,678,000		$	4,435,000		$	3,408,000
Additions based on tax positions related to the current year	1,695,000			1,677,000			941,000
Additions for tax positions in prior years	657,000			283,000			289,000
Reductions for tax positions in prior years	(38,000		)	(163,000		)	(63,000		)
Reductions as a result of completed audit examinations	—			(1,554,000		)	—
Reductions as a result of a lapse of the applicable statute of limitations	(600,000		)	—			(140,000		)
End of year	$	6,392,000		$	4,678,000		$	4,435,000

Stock-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Schedule of Weighted-Average Assumptions

The fair value of each option grant was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions for the indicated periods:



	2019			2018			2017
Dividend yield⁽¹⁾	2.0		%	2.1		%	2.1		%
Expected volatility ⁽²⁾	23.9		%	26.0		%	26.7		%
Risk-free interest rate ⁽³⁾	1.8		%	2.7		%	2.0		%
Expected term of options (in years) ⁽⁴⁾	4.2			4.2			4.2
Weighted-average grant-date fair value	$	4		$	5		$	4

(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.

Summary of Stock Option Activity

A summary of the status of the Company’s employee stock option plan at December 31, 2019, 2018 and 2017, and changes during the same periods are presented in the tables below.



	2019
	Shares (000)		Wtd. Avg. Ex. Price		Wtd. Avg. Remaining Contract Life	Aggregate Intrinsic Value (000)
Outstanding at Beginning of Year	8,944		$	18
Granted	1,049		25
Exercised	(4,402	)	16			$	36,294
Forfeited	(156	)	20
Outstanding at End of Year	5,435		20		3.1 Yrs	$	47,170
Exercisable at End of Year	1,859		$	18	2.2 Yrs	$	20,484



	2018
	Shares (000)		Wtd. Avg. Ex. Price		Wtd. Avg. Remaining Contract Life	Aggregate Intrinsic Value (000)
Outstanding at Beginning of Year	11,837		$	16
Granted	1,613		22
Exercised	(4,278	)	15			$	38,097
Forfeited	(228	)	18
Outstanding at End of Year	8,944		18		2.8 Yrs	$	24,881
Exercisable at End of Year	4,101		$	16	1.7 Yrs	$	16,162



	2017
	Shares (000)		Wtd. Avg. Ex. Price		Wtd. Avg. Remaining Contract Life	Aggregate Intrinsic Value (000)
Outstanding at Beginning of Year	14,252		$	15
Granted	1,295		20
Exercised	(3,476	)	13			$	25,156
Forfeited	(234	)	16
Outstanding at End of Year	11,837		16		2.7 Yrs	$	58,202
Exercisable at End of Year	5,297		$	15	2 Yrs	$	32,152

Schedule of Non-Vested Stock Option Activity

A summary of the status of the Company’s non-vested employee stock option activity for the years ended December 31, 2019, 2018, and 2017, are presented in the table below:



	2019				2018				2017
	Shares (000)		Wtd. Avg Grant Date Fair Value		Shares (000)		Wtd. Avg Grant Date Fair Value		Shares (000)		Wtd. Avg Grant Date Fair Value
Nonvested Stock Options at Beginning of Year	4,842		$	4	6,540		$	4	9,397		$	4
Granted	1,049		4		1,613		5		1,295		4
Vested	(2,165	)	4		(3,089	)	4		(3,941	)	4
Forfeited	(151	)	4		(222	)	4		(211	)	4
Nonvested Stock Options at End of Year	3,575		$	4	4,842		$	4	6,540		$	4

Schedule of Restricted Shares



	2019			2018			2017
Vesting Period⁽¹⁾	Shares Granted	Market Price at Vesting Date		Shares Granted	Market Price at Vesting Date		Shares Granted	Market Price at Vesting Date
1 Year	39,627	$	22.19	—	$	—	—	$	—
3 Years	64,718	20.40		—	—		—	—
4 Years	773,698	20.68 - 28.98		762,749	20.21 - 23.14		628,015	18.97 - 21.33
5 Years	254,988	20.68 - 28.98		279,420	20.21 - 23.14		228,630	18.97 - 21.33
	1,133,031	$20.40 - 28.98		1,042,169	$20.21 - 23.14		856,645	$18.97 - 21.33
(1) Each of these awards cliff vest after the restriction period with no additional restrictions.

Schedule of Employee Stock Purchase Plan

The following table summarizes shares sold to employees under the 2013 Plan in the years ended December 31, 2019, 2018 and 2017:



Plan	2019	2018	2017	Cumulative Shares Issued in 2019	Weighted Average Fair Value 2019
2013 Employee Stock Purchase Plan	173,013	177,846	175,479	1,145,856	$	21.40

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Schedule of Automotive and Other Segment Reporting



	2019		2018		2017
Revenue:
Automotive Products
United States	$	569,939,756	$	583,672,971	$	567,492,812
Germany	296,276,971		333,002,878		351,123,204
Japan	225,577,146		209,311,790		185,261,067
Mexico	160,967,900		106,111,515		93,603,796
Other Countries	557,775,114		559,099,142		560,646,589
Other	48,360,519		42,865,401		36,745,110
Total	$	1,858,897,406	$	1,834,063,697	$	1,794,872,578
Income (Loss) from Operations:
Automotive Products	$	473,546,112	$	495,471,799	$	512,895,699
Other	14,991,492		12,653,748		10,462,653
Total	$	488,537,604	$	508,125,547	$	523,358,352
Assets:
Automotive Products	$	1,463,030,286	$	1,449,910,935	$	1,472,061,650
Other	16,000,669		14,333,098		9,576,514
Corporate	689,772,238		621,190,035		870,415,748
Total	$	2,168,803,193	$	2,085,434,068	$	2,352,053,912
Depreciation & Amortization:
Automotive Products	$	97,520,972	$	97,279,052	$	95,378,100
Other	481,861		422,844		300,935
Corporate	6,700,141		4,484,918		3,891,873
Total	$	104,702,974	$	102,186,814	$	99,570,908
Capital Expenditures:
Automotive Products	$	63,537,512	$	84,337,455	$	82,703,576
Other	1,704,045		1,447,494		170,357
Corporate	19,338,698		205,621		21,166,986
Total	$	84,580,255	$	85,990,570	$	104,040,919

Schedule of Major Product Line Revenues

Other includes Dimmable Aircraft Windows and Fire Protection Products. Major product line revenues included within these segments are as follows:



	2019		2018		2017
Automotive Products
Automotive Mirrors	$	1,638,600,272	$	1,598,589,777	$	1,573,222,820
HomeLink^® Modules*	171,936,615		192,608,519		184,904,648
Total Automotive Products	$	1,810,536,887	$	1,791,198,296	$	1,758,127,468

Other Products Revenue	$	48,360,519	$	42,865,401	$	36,745,110

Total Revenue	$	1,858,897,406	$	1,834,063,697	$	1,794,872,578

*Excludes HomeLink^® revenue integrated into automotive mirrors.

Schedule of Automotive Customers Individually Accounted For 10% or More of Net Sales



	Toyota Motor Company		Volkswagen Group		General Motors		Daimler Group		Ford Motor Company
2019	13	%	14	%	11	%	#		#
2018	13	%	15	%	#		10	%	#
2017	12	%	15	%	#		10	%	10	%

# - Less than 10 percent.

Quarterly Financial Information (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

The following table sets forth selected financial information for all of the quarters during the years ended December 31, 2019 and 2018 (in thousands, except per share data):




	First				Second				Third				Fourth
	2019		2018		2019		2018		2019		2018		2019		2018
Net Sales	$	468,589	$	465,420	$	468,711	$	454,981	$	477,761	$	460,253	$	443,836	$	453,409
Gross Profit	169,645		172,628		176,538		172,804		180,321		172,990		161,805		172,044
Operating Income	121,596		128,515		127,905		126,683		128,136		127,428		110,901		125,499
Net Income	104,280		111,249		108,959		109,024		111,898		111,336		99,547		106,275
Earnings Per Share (Basic)⁽¹⁾	$	0.40	$	0.40	$	0.42	$	0.40	$	0.44	$	0.42	$	0.39	$	0.41
Earnings Per Share (Diluted)⁽¹⁾	$	0.40	$	0.40	$	0.42	$	0.40	$	0.44	$	0.42	$	0.39	$	0.41
⁽¹⁾Basic and diluted earnings per share are computed independently for each quarter presented. Therefore the sum of quarterly basic and diluted per share information may not equal annual basis and diluted earnings per share.

Comprehensive Income (Tables)

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)



	For the Twelve Months ended December 31,
	2019			2018			2017
Foreign currency translation adjustments:
Balance at beginning of period	$	(1,674,887	)	$	645,030		$	(2,862,999	)
Other comprehensive (loss) income before reclassifications	(709,702		)	(2,319,917		)	3,508,029
Net current-period change	(709,702		)	(2,319,917		)	3,508,029
Balance at end of period	(2,384,589		)	(1,674,887		)	645,030
Unrealized gains (losses) on available-for-sale securities:
Balance at beginning of period	74,549			6,626,379			2,788,975
ASU 2016-01 adoption impact	—			(6,642,727		)	—
Other comprehensive income before reclassifications	1,403,521			1,675,823			4,444,360
Amounts reclassified from accumulated other comprehensive income	(382,584		)	(1,584,926		)	(606,956		)
Net current-period change	1,020,937			(6,551,830		)	3,837,404
Balance at end of period	1,095,486			74,549			6,626,379
Unrealized gains (losses) on derivatives:
Balance at beginning of period	—			(78,026		)	(1,197,281		)
Other comprehensive income before reclassifications	—			175,308			248,042
Amounts reclassified from accumulated other comprehensive income	—			(97,282		)	871,213
Net current-period change	—			78,026			1,119,255
Balance at end of period	—			—			(78,026		)

Accumulated other comprehensive (loss) income, end of period	$	(1,289,103	)	$	(1,600,338	)	$	7,193,383

Reclassification out of Accumulated Other Comprehensive Income

The following table presents details of reclassifications out of other comprehensive income for the twelve months ended December 31, 2019, 2018 and 2017.



Details about Accumulated Other Comprehensive Income Components										Affected Line item in the Statement of Consolidated Income
	For the Twelve Months ended December 31,
	2019			2018			2017
Unrealized gains on available-for-sale debt securities
Realized gain on sale of securities	$	484,283		$	2,006,235		$	933,778		Other income (expense), net
Provision for income taxes	(101,699		)	(421,309		)	(326,822		)	Provision for Income Taxes
Total reclassifications for the period	$	382,584		$	1,584,926		$	606,956		Net of tax

Unrealized gains (losses) on derivatives
Realized loss on interest rate swap	$	—		$	123,142		$	(1,340,329	)	Other income (expense), net
Provision for income taxes	—			(25,860		)	469,116			Provision for Income Taxes
	$	—		$	97,282		$	(871,213	)	Net of tax

Total reclassifications for the period	$	382,584		$	1,682,208		$	(264,257	)	Net of tax

Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The carrying value of Goodwill as of both December 31, 2019 and December 31, 2018 was $307.4 million as set forth in the table below.



	Carrying Amount
Balance as of December 31, 2018	$	307,365,845
Acquisitions	—
Divestitures	—
Impairments	—
Other	—
Balance as of December 31, 2019	$	307,365,845

Schedule of Intangible Assets

The Intangible Assets and related change in carrying values are set forth in the table below as of December 31, 2019 and December 31, 2018.

As of December 31, 2019:



Other Intangible Assets	Gross		Accumulated Amortization			Net		Assumed Useful Life
HomeLink^®Trade Names and Trademarks	$	52,000,000	$	—		$	52,000,000	Indefinite
HomeLink^®Technology	180,000,000		(93,750,000		)	$	86,250,000	12 years
Existing Customer Platforms	43,000,000		(26,875,000		)	$	16,125,000	10 years
Exclusive Licensing Agreement	96,000,000		—			$	96,000,000	Indefinite
Total other identifiable intangible assets	371,000,000		(120,625,000		)	250,375,000

As of December 31, 2018:



Other Intangible Assets	Gross		Accumulated Amortization			Net		Assumed Useful Life
HomeLink^®Trade Names and Trademarks	$	52,000,000	$	—		$	52,000,000	Indefinite
HomeLink^®Technology	180,000,000		(78,750,000		)	$	101,250,000	12 years
Existing Customer Platforms	43,000,000		(22,575,000		)	$	20,425,000	10 years
Exclusive Licensing Agreement	96,000,000		—			$	96,000,000	Indefinite
Total other identifiable intangible assets	371,000,000		(101,325,000		)	269,675,000

Revenue (Tables)

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table disaggregates the Company’s Automotive and Other revenue by major source for the twelve month periods ended December 31, 2019 and 2018:



	For the Twelve Months Ended December 31,
Revenue	2019		2018
Automotive Segment
Automotive Mirrors & Electronics	$	1,638,600,272	$	1,598,589,777
HomeLink Modules*	171,936,615		192,608,519
Total Automotive Products	$	1,810,536,887	$	1,791,198,296

Other Segment
Fire Protection Products	$	23,740,261	$	22,109,784
Windows Products	24,620,258		20,755,617
Total Other	$	48,360,519	$	42,865,401

*Excludes HomeLink revenue related to HomeLink modules integrated into automotive mirrors.



	For the Twelve Months ended December 31,
Revenue	2019		2018		2017
Automotive Products
U.S.	$	569,939,756	$	583,672,971	$	567,492,812
Germany	296,276,971		333,002,878		351,123,204
Japan	225,577,146		209,311,790		185,261,067
Mexico	160,967,900		106,111,515		93,603,796
Other	557,775,114		559,099,142		560,646,589
Total Automotive Products	$	1,810,536,887	$	1,791,198,296	$	1,758,127,468
Other Products (U.S.)	48,360,519		42,865,401		36,745,110
Total Revenue	$	1,858,897,406	$	1,834,063,697	$	1,794,872,578

Summary of Significant Accounting and Reporting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) plan shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares
Summary Of Significant Accounting And Reporting Policies [Line Items]
Technology investments	$ 9,000,000.0	$ 3,900,000
Equity Investment losses were considered to be other than temporary	0	0
Allowance for obsolete and slow moving inventories	7,600,000	7,800,000
Depreciation expense	82,300,000	79,700,000	$ 77,000,000.0
Advertising and promotional costs	3,000,000.0	2,500,000	2,600,000
Repair and maintenance of plant and equipment	$ 28,900,000	$ 28,900,000	$ 24,600,000
Weighted average remaining lease term	2 years
Weighted average discount rate	2.90%
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be antidilutive \| shares	247,855	698,019	910,105
Minimum
Summary Of Significant Accounting And Reporting Policies [Line Items]
Remaining lease term	1 year
Maximum
Summary Of Significant Accounting And Reporting Policies [Line Items]
Remaining lease term	5 years
Buildings and improvements \| Minimum
Summary Of Significant Accounting And Reporting Policies [Line Items]
Minimum estimated useful life, in years	7 years
Buildings and improvements \| Maximum
Summary Of Significant Accounting And Reporting Policies [Line Items]
Minimum estimated useful life, in years	30 years
Machinery and equipment \| Minimum
Summary Of Significant Accounting And Reporting Policies [Line Items]
Minimum estimated useful life, in years	3 years
Machinery and equipment \| Maximum
Summary Of Significant Accounting And Reporting Policies [Line Items]
Minimum estimated useful life, in years	10 years
Employee Stock Option
Summary Of Significant Accounting And Reporting Policies [Line Items]
Number of plans \| plan	2

Summary of Significant Accounting and Reporting Policies (Schedule Of Allowance For Doubtful Accounts) (Details) - Allowance for Doubtful Accounts - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Activity in the Company’s allowance for doubtful accounts
Beginning Balance	$ 2,746,647	$ 2,714,533	$ 2,917,424
Net Additions/ (Reductions) to Costs and Expenses	0	0	0
Deductions and Other Adjustments	(295,354)	32,114	(202,891)
Ending Balance	$ 2,451,293	$ 2,746,647	$ 2,714,533

Summary of Significant Accounting and Reporting Policies (Schedule of Assets or Liabilities Having Recurring Measurements) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	$ 296,321,622	$ 217,025,278
Total	567,597,380	520,567,359
Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	50,099,795	150,299,384
Market Value	3,557,798
Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	25,791,029
Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	58,432,823	9,176,227
Market Value	6,088,190	56,483,720
Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	29,219,685	6,967,700
Market Value	22,815,998	60,369,930
Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	2,631,750	2,219,688
Municipal Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	72,638,690	18,025,432
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	296,321,622	217,025,278
Total	352,610,965	369,544,350
Level 1 \| Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	50,099,795	150,299,384
Market Value	3,557,798
Level 1 \| Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0
Level 1 \| Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Market Value	0	0
Level 1 \| Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0
Market Value	0	0
Level 1 \| Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	2,631,750	2,219,688
Level 1 \| Municipal Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	0	0
Total	214,986,415	151,023,009
Level 2 \| Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Market Value	0
Level 2 \| Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	25,791,029
Level 2 \| Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	58,432,823	9,176,227
Market Value	6,088,190	56,483,720
Level 2 \| Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	29,219,685
Market Value	22,815,998	60,369,930
Level 2 \| Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Level 2 \| Municipal Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	72,638,690	18,025,432
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	0	0
Level 3 \| Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Market Value	0
Level 3 \| Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0
Level 3 \| Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Market Value	0	0
Level 3 \| Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0
Market Value	0	0
Level 3 \| Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	0	0
Level 3 \| Municipal Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Value	$ 0	$ 0

Summary of Significant Accounting and Reporting Policies (Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value Of Investment Securities) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Long-Term Investments:
Cost	$ 269,889,067	$ 303,467,531
Unrealized gains	1,974,255	440,807
Unrealized losses	(587,564)	(366,257)
Total	271,275,758	303,542,081
Certificates of Deposit
Short-Term Investments:
Cost	50,099,795	150,299,384
Gains	0	0
Losses	0	0
Market Value	50,099,795	150,299,384
Long-Term Investments:
Cost	3,500,000
Gains	58,808
Losses	(1,010)
Market Value	3,557,798
Asset-backed Securities
Long-Term Investments:
Cost	25,971,156
Gains	0
Losses	(180,127)
Market Value	25,791,029
Government Securities
Short-Term Investments:
Cost	58,343,911	9,186,586
Gains	99,917	0
Losses	(11,005)	(10,359)
Market Value	58,432,823	9,176,227
Long-Term Investments:
Cost	6,012,705	56,280,552
Gains	75,485	205,553
Losses	0	(2,385)
Market Value	6,088,190	56,483,720
Municipal Bonds
Long-Term Investments:
Cost	71,997,996	17,840,518
Gains	1,036,116	184,914
Losses	(395,422)	0
Market Value	72,638,690	18,025,432
Corporate Bonds
Short-Term Investments:
Cost	29,025,624	6,981,305
Gains	194,061	0
Losses	0	(13,605)
Market Value	29,219,685	6,967,700
Long-Term Investments:
Cost	22,306,130	60,659,498
Gains	509,868	50,340
Losses	0	(339,908)
Market Value	22,815,998	60,369,930
Other
Short-Term Investments:
Cost	2,631,750	2,219,688
Gains	0	0
Losses	0	0
Market Value	$ 2,631,750	2,219,688
Common Stocks
Long-Term Investments:
Cost		0
Gains		0
Losses		0
Market Value		$ 0

Summary of Significant Accounting and Reporting Policies (Schedule of Unrealized Losses on Investments) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Aggregate Unrealized Losses, Less than one year	$ 587,564	$ 365,824
Aggregate Fair Value, Less than one year	90,721,081	68,722,980
Aggregate Unrealized Losses, Greater than one year	0	433
Aggregate Fair Value, Greater than one year	0	3,000,000
Aggregate Unrealized Losses, Total	587,564	366,257
Aggregate Fair Value, Total	$ 90,721,081	$ 71,722,980

Summary of Significant Accounting and Reporting Policies (Fixed Income Securities Contractual Maturity) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Total	$ 271,275,758	$ 303,542,081
Fixed Income Securities
Debt Securities, Available-for-sale [Line Items]
Due within one year	137,752,302
Due between one and five years	43,125,222
Due over five years	87,766,483
Total	$ 268,644,007

Summary of Significant Accounting and Reporting Policies (Inventories) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Raw materials	$ 164,974,553	$ 139,058,541
Work-in-process	33,069,255	35,386,615
Finished goods	50,898,047	50,836,443
Total Inventory	$ 248,941,855	$ 225,281,599

Summary of Significant Accounting and Reporting Policies (Leases) (Details)	Dec. 31, 2019 USD ($)
Accounting Policies [Abstract]
2020	$ 786,807
2021	297,316
2022	145,154
2023	19,296
Thereafter	15,105
Total future minimum lease payments	1,263,678
Less imputed interest	(84,964)
Total	$ 1,178,714

Summary of Significant Accounting and Reporting Policies (Schedule of Earnings Per Share, Basic And Diluted) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic Earnings Per Share
Net income	$ 99,547,000	$ 111,898,000	$ 108,959,000	$ 104,280,000	$ 106,275,000	$ 111,336,000	$ 109,024,000	$ 111,249,000	$ 424,683,939	$ 437,883,097	$ 406,791,922
Less: Allocated to participating securities									5,028,813	3,836,536	2,562,473
Net Income available to common shareholders									$ 419,655,126	$ 437,883,097	$ 406,791,922
Basic weighted average shares outstanding (in shares)									251,766,382	267,794,786	285,864,997
Net Income per share - Basic (in dollars per share)	$ 0.39	$ 0.44	$ 0.42	$ 0.40	$ 0.41	$ 0.42	$ 0.40	$ 0.40	$ 1.67	$ 1.64	$ 1.42
Diluted Earnings Per Share
Allocation of Net Income used in basic computation									$ 419,655,126	$ 437,883,097	$ 406,791,922
Reallocation of undistributed earnings									21,104	21,007	19,398
Net Income available to common shareholders - Diluted									$ 419,676,230	$ 437,904,104	$ 406,811,320
Basic weighted average shares outstanding (in shares)									251,766,382	267,794,786	285,864,997
Additional weighted average dilutive common stock equivalents (in shares)									1,506,608	2,082,563	2,361,092
Diluted weighted average shares outstanding (in shares)									253,272,990	269,877,349	288,226,089
Net income per share - Diluted (in dollars per share)	$ 0.39	$ 0.44	$ 0.42	$ 0.40	$ 0.41	$ 0.42	$ 0.40	$ 0.40	$ 1.66	$ 1.62	$ 1.41

Debt and Financing Arrangements (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Oct. 15, 2018
Revolver
Debt Instrument [Line Items]
Principal amount			$ 150,000,000
Additional principal amount available (up to)			100,000,000
Amount outstanding	$ 0	$ 0
Swing loans
Debt Instrument [Line Items]
Additional principal amount available (up to)			20,000,000
Letters of Credit
Debt Instrument [Line Items]
Additional principal amount available (up to)			$ 20,000,000

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
TCJA, provision reduction to income tax expense			$ 38,400
Income taxes paid	$ 74,900	$ 86,900	126,000
Unrecognized tax benefits accrued interest	$ 574	$ 315	$ 433

Income Taxes (Schedule Of Components Of Provision For Income Taxes) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Currently payable:
Federal	$ 73,563,685	$ 83,010,387	$ 133,166,194
State	3,765,929	3,743,781	3,984,000
Foreign	1,468,018	1,776,837	2,440,000
Total	78,797,632	88,531,005	139,590,194
Deferred income tax (benefit) expense:
Primarily federal	(3,066,237)	(4,367,155)	(14,585,412)
Provision for income taxes	$ 75,731,395	$ 84,163,850	$ 125,004,782

Income Taxes (Schedule Of Effective Income Tax Rates Different From Statutory Federal Income Tax Rates) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	21.00%	21.00%	35.00%
State income taxes, net of federal income tax benefit	0.60%	0.60%	0.50%
Domestic production exclusion	0.00%	0.00%	(2.80%)
Research tax credit	(1.10%)	(0.80%)	(0.80%)
Increase in reserve for uncertain tax provisions	0.30%	0.10%	0.10%
Change in tax rate on deferred taxes	0.00%	0.50%	(7.20%)
Foreign tax credit	(0.10%)	(0.10%)	(0.80%)
Foreign derived intangible income deduction	(4.80%)	(4.60%)	0.00%
Stock compensation	(1.10%)	(1.00%)	(1.00%)
Other	0.30%	0.40%	0.50%
Effective income tax rate	15.10%	16.10%	23.50%

Income Taxes (Schedule Of Deferred Income Tax Assets And Liabilities) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Assets:
Accruals not currently deductible	$ 6,478,146	$ 5,111,242
Stock based compensation	9,100,745	9,586,372
Other	66,830	356,039
Total deferred income tax assets	15,645,721	15,053,653
Liabilities:
Excess tax over book depreciation	(30,725,471)	(39,835,025)
Goodwill	(27,799,640)	(23,341,226)
Intangible assets	(6,171,628)	(5,089,042)
Other	(2,403,131)	(1,309,849)
Total deferred income tax liability	(67,099,870)	(69,575,142)
Net deferred income taxes	$ (51,454,149)	$ (54,521,489)

Income Taxes (Schedule Of Reconciliation Of Beginning And Ending Amount Of Unrecognized Tax Benefits ) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Beginning of year	$ 4,678,000	$ 4,435,000	$ 3,408,000
Additions based on tax positions related to the current year	1,695,000	1,677,000	941,000
Additions for tax positions in prior years	657,000	283,000	289,000
Reductions for tax positions in prior years	(38,000)	(163,000)	(63,000)
Reductions as a result of completed audit examinations	0	(1,554,000)	0
Reductions as a result of a lapse of the applicable statute of limitations	(600,000)	0	(140,000)
End of year	$ 6,392,000	$ 4,678,000	$ 4,435,000

Employee Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
Employee Benefit Plan (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Company's contributions under 401(k) retirement savings plan	$ 8.7	$ 8.2	$ 7.7
Deferred Compensation Arrangement With Individual, Tranche Two
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation arrangement vesting percentage	100.00%
Deferred compensation arrangement, service period	3 years
Deferred Compensation Arrangement With Individual, Tranche One
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation arrangement vesting percentage	50.00%
Deferred Compensation Arrangement With Individual, Tranche One \| Minimum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation arrangement, service period	2 years
Deferred Compensation Arrangement With Individual, Tranche One \| Maximum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation arrangement, service period	3 years

Stock-Based Compensation Plans (Narrative) (Details)	11 Months Ended	12 Months Ended			60 Months Ended	72 Months Ended	84 Months Ended
Stock-Based Compensation Plans (Narrative) (Details)	Dec. 31, 2019 USD ($) plan shares	Dec. 31, 2019 USD ($) plan shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2019 USD ($) plan shares	Dec. 31, 2019 USD ($) plan shares	Dec. 31, 2019 USD ($) plan shares	Dec. 31, 2013 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, granted (in shares)		1,049,000	1,613,000	1,295,000
Stock Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans \| plan	2	2			2	2	2
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost \| $	$ 2,224,328	$ 2,224,328			$ 2,224,328	$ 2,224,328	$ 2,224,328
Amortization expense \| $		$ 897,136	$ 0	$ 0
Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares approved (in shares)	45,000,000	45,000,000			45,000,000	45,000,000	45,000,000
Shares issued under plan (in shares)	4,919,256	4,919,256			4,919,256	4,919,256	4,919,256
Options granted net of shares from canceled/expired options (in shares)	796,635
Restricted period, maximum, in years		10 years
Shares granted with restriction period (in shares)		3,315,482
Shares, granted (in shares)	854,633
Omnibus Incentive Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period		1 year
Award expiration period		5 years
Omnibus Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period		5 years
Award expiration period		10 years
Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares approved (in shares)	9,000,000	9,000,000			9,000,000	9,000,000	9,000,000
Shares granted with restriction period (in shares)		3,315,482
Shares, granted (in shares)					5,762,672
Unearned stock-based compensation \| $	$ 47,139,370	$ 47,139,370			$ 47,139,370	$ 47,139,370	$ 47,139,370
Amortization expense \| $		$ 13,770,917	$ 8,841,985	$ 5,353,339
Employee Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares approved (in shares)	24,000,000	24,000,000			24,000,000	24,000,000	24,000,000
Options granted net of shares from canceled/expired options (in shares)						12,903,592
Unrecognized compensation cost \| $	$ 6,316,567	$ 6,316,567			$ 6,316,567	$ 6,316,567	$ 6,316,567
Weighted-average period for unrecognized compensation cost expected to be recognized		1 year 10 months 24 days
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares approved (in shares)								2,000,000
Shares, granted (in shares)		173,013	177,846	175,479			1,145,856
ESPP discount rate		85.00%
Discount recognized as compensation expense		15.00%

Stock-Based Compensation Plans (Schedule of Weighted-Average Assumptions) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Dividend yield	2.00%	2.10%	2.10%
Expected volatility	23.90%	26.00%	26.70%
Risk-free interest rate	1.80%	2.70%	2.00%
Expected term of options (in years)	4 years 2 months 12 days	4 years 2 months 12 days	4 years 2 months 12 days
Weighted-average grant-date fair value (in dollars per share)	$ 4	$ 5	$ 4

Stock-Based Compensation Plans (Summary of Stock Option Activity) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares (000)
Shares, Outstanding at Beginning of Year (in shares)	8,944	11,837	14,252
Shares, Granted (in shares)	1,049	1,613	1,295
Shares, Exercised (in shares)	(4,402)	(4,278)	(3,476)
Shares, Forfeited (in shares)	(156)	(228)	(234)
Shares, Outstanding at End of Year (in shares)	5,435	8,944	11,837
Shares, Exercisable at End of Year (in shares)	1,859	4,101	5,297
Wtd. Avg Grant Date Fair Value
Wtd. Avg. Ex. Price, Outstanding at Beginning of Year (in dollars per share)	$ 18	$ 16	$ 15
Wtd. Avg. Ex. Price, Granted (in dollars per share)	25	22	20
Wtd. Avg. Ex. Price, Exercised (in dollars per share)	16	15	13
Wtd. Avg. Ex. Price, Forfeited (in dollars per share)	20	18	16
Wtd. Avg. Ex. Price, Outstanding at End of Year (in dollars per share)	20	18	16
Wtd. Avg. Ex. Price, Exercisable at End of Year (in dollars per share)	$ 18	$ 16	$ 15
Option expiration period, years	3 years 1 month 6 days	2 years 9 months 18 days	2 years 8 months 12 days
Wtd. Avg. Remaining Contract Life, Exercisable at End of Year	2 years 2 months 12 days	1 year 8 months 12 days	2 years
Aggregate Intrinsic Value, Exercised	$ 36,294	$ 38,097	$ 25,156
Aggregate Intrinsic Value, Outstanding at End of Year	47,170	24,881	58,202
Aggregate Intrinsic Value, Exercisable at End of Year	$ 20,484	$ 16,162	$ 32,152

Stock-Based Compensation Plans (Schedule of Non-Vested Stock Option Activity) (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares (000)
Shares, Nonvested stock options at Beginning of Year (in shares)	4,842	6,540	9,397
Shares, Granted (in shares)	1,049	1,613	1,295
Shares, Vested (in shares)	(2,165)	(3,089)	(3,941)
Shares, Forfeited (in shares)	(151)	(222)	(211)
Shares, Nonvested stock options at End of Year (in shares)	3,575	4,842	6,540
Wtd. Avg Grant Date Fair Value
Wtd. Avg Grant Date Fair Value, Nonvested stock options at Beginning of Year (in dollars per share)	$ 4	$ 4	$ 4
Wtd. Avg Grant Date Fair Value, Granted (in dollars per share)	4	5	4
Wtd. Avg Grant Date Fair Value, Vested (in dollars per share)	4	4	4
Wtd. Avg Grant Date Fair Value, Forfeited (in dollars per share)	4	4	4
Wtd. Avg Grant Date Fair Value, Nonvested stock options at End of Year (in dollars per share)	$ 4	$ 4	$ 4

Stock-Based Compensation Plans (Vested Restricted Stocks) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market Price at Vesting Date (in shares)	$ 25	$ 22	$ 20
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	1,133,031	1,042,169	856,645
Restricted Stock \| 1 Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	39,627	0	0
Market Price at Vesting Date (in shares)	$ 22.19
Restricted Stock \| 3 Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	64,718	0	0
Market Price at Vesting Date (in shares)	$ 20.40
Restricted Stock \| 3 Years \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market Price at Vesting Date (in shares)	20.40	$ 20.21	$ 18.97
Restricted Stock \| 3 Years \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market Price at Vesting Date (in shares)	$ 28.98	$ 23.14	$ 21.33
Restricted Stock \| 4 Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	773,698	762,749	628,015
Restricted Stock \| 4 Years \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market Price at Vesting Date (in shares)	$ 20.68	$ 20.21	$ 18.97
Restricted Stock \| 4 Years \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market Price at Vesting Date (in shares)	$ 28.98	$ 23.14	$ 21.33
Restricted Stock \| 5 Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	254,988	279,420	228,630
Restricted Stock \| 5 Years \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market Price at Vesting Date (in shares)	$ 20.68	$ 20.21	$ 18.97
Restricted Stock \| 5 Years \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market Price at Vesting Date (in shares)	$ 28.98	$ 23.14	$ 21.33

Stock-Based Compensation Plans (Employee Stock Purchase Plan) (Details) - $ / shares	12 Months Ended			84 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, granted (in shares)	1,049,000	1,613,000	1,295,000
Wtd. Avg Grant Date Fair Value, Granted (in dollars per share)	$ 4	$ 5	$ 4
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, granted (in shares)	173,013	177,846	175,479	1,145,856
Wtd. Avg Grant Date Fair Value, Granted (in dollars per share)				$ 21.40

Segment Reporting (Schedule of Automotive and Other Segment Reporting) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 443,836,000	$ 477,761,000	$ 468,711,000	$ 468,589,000	$ 453,409,000	$ 460,253,000	$ 454,981,000	$ 465,420,000	$ 1,858,897,406	$ 1,834,063,697	$ 1,794,872,578
Income (Loss) from Operations	110,901,000	$ 128,136,000	$ 127,905,000	$ 121,596,000	125,499,000	$ 127,428,000	$ 126,683,000	$ 128,515,000	488,537,604	508,125,547	523,358,352
Assets	2,168,803,193				2,085,434,068				2,168,803,193	2,085,434,068	2,352,053,912
Depreciation & Amortization									104,702,974	102,186,814	99,570,908
Capital Expenditures									84,580,255	85,990,570	104,040,919
Corporate
Segment Reporting Information [Line Items]
Assets	689,772,238				621,190,035				689,772,238	621,190,035	870,415,748
Depreciation & Amortization									6,700,141	4,484,918	3,891,873
Capital Expenditures									19,338,698	205,621	21,166,986
Automotive Products
Segment Reporting Information [Line Items]
Revenues									1,810,536,887	1,791,198,296	1,758,127,468
Income (Loss) from Operations									473,546,112	495,471,799	512,895,699
Automotive Products \| Operating Segments
Segment Reporting Information [Line Items]
Assets	1,463,030,286				1,449,910,935				1,463,030,286	1,449,910,935	1,472,061,650
Depreciation & Amortization									97,520,972	97,279,052	95,378,100
Capital Expenditures									63,537,512	84,337,455	82,703,576
Other
Segment Reporting Information [Line Items]
Revenues									48,360,519	42,865,401	36,745,110
Income (Loss) from Operations									14,991,492	12,653,748	10,462,653
Other \| Operating Segments
Segment Reporting Information [Line Items]
Assets	$ 16,000,669				$ 14,333,098				16,000,669	14,333,098	9,576,514
Depreciation & Amortization									481,861	422,844	300,935
Capital Expenditures									1,704,045	1,447,494	170,357
United States \| Automotive Products
Segment Reporting Information [Line Items]
Revenues									569,939,756	583,672,971	567,492,812
Germany \| Automotive Products
Segment Reporting Information [Line Items]
Revenues									296,276,971	333,002,878	351,123,204
Japan \| Automotive Products
Segment Reporting Information [Line Items]
Revenues									225,577,146	209,311,790	185,261,067
Mexico \| Automotive Products
Segment Reporting Information [Line Items]
Revenues									160,967,900	106,111,515	93,603,796
Other Countries \| Automotive Products
Segment Reporting Information [Line Items]
Revenues									$ 557,775,114	$ 559,099,142	$ 560,646,589

Segment Reporting (Schedule of Major Product Line Revenues) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from External Customer [Line Items]
Revenues	$ 443,836,000	$ 477,761,000	$ 468,711,000	$ 468,589,000	$ 453,409,000	$ 460,253,000	$ 454,981,000	$ 465,420,000	$ 1,858,897,406	$ 1,834,063,697	$ 1,794,872,578
Automotive Products
Revenue from External Customer [Line Items]
Revenues									1,810,536,887	1,791,198,296	1,758,127,468
Automotive Products \| Automotive Mirrors
Revenue from External Customer [Line Items]
Revenues									1,638,600,272	1,598,589,777	1,573,222,820
Automotive Products \| HomeLink Modules
Revenue from External Customer [Line Items]
Revenues									171,936,615	192,608,519	184,904,648
Other
Revenue from External Customer [Line Items]
Revenues									48,360,519	42,865,401
Other \| Other Products Revenue
Revenue from External Customer [Line Items]
Revenues									$ 48,360,519	$ 42,865,401	$ 36,745,110

Segment Reporting (Schedule of Automotive Customers Individually Accounted For 10% or More of Net Sales) (Details) - automotive_customer	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue, Major Customer [Line Items]
Percentage net sales invoiced and paid in foreign currencies	7.00%	8.00%	8.00%
Number of customers which individually accounted for 10% or more of net sales	3
Customer concentration risk \| Toyota Motor Company
Revenue, Major Customer [Line Items]
Percentage of revenue individually accounted by customers (less than 10% for General Motor Company in 2018 and 2017, Daimler Group in 2019, and Ford in 2019 and 2017)	13.00%	13.00%	12.00%
Customer concentration risk \| Volkswagen Group
Revenue, Major Customer [Line Items]
Percentage of revenue individually accounted by customers (less than 10% for General Motor Company in 2018 and 2017, Daimler Group in 2019, and Ford in 2019 and 2017)	14.00%	15.00%	15.00%
Customer concentration risk \| General Motors
Revenue, Major Customer [Line Items]
Percentage of revenue individually accounted by customers (less than 10% for General Motor Company in 2018 and 2017, Daimler Group in 2019, and Ford in 2019 and 2017)	11.00%	10.00%	10.00%
Customer concentration risk \| Daimler Group
Revenue, Major Customer [Line Items]
Percentage of revenue individually accounted by customers (less than 10% for General Motor Company in 2018 and 2017, Daimler Group in 2019, and Ford in 2019 and 2017)	10.00%	10.00%	10.00%
Customer concentration risk \| Ford Motor Company
Revenue, Major Customer [Line Items]
Percentage of revenue individually accounted by customers (less than 10% for General Motor Company in 2018 and 2017, Daimler Group in 2019, and Ford in 2019 and 2017)		10.00%	10.00%

Quarterly Financial Information (Details) - USD ($)	3 Months Ended								12 Months Ended
Quarterly Financial Information (Details) - USD ($)	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Net Sales	$ 443,836,000	$ 477,761,000	$ 468,711,000	$ 468,589,000	$ 453,409,000	$ 460,253,000	$ 454,981,000	$ 465,420,000	$ 1,858,897,406	$ 1,834,063,697	$ 1,794,872,578
Gross Profit	161,805,000	180,321,000	176,538,000	169,645,000	172,044,000	172,990,000	172,804,000	172,628,000	688,307,969	690,466,692	694,528,266
Operating Income	110,901,000	128,136,000	127,905,000	121,596,000	125,499,000	127,428,000	126,683,000	128,515,000	488,537,604	508,125,547	523,358,352
Net income	$ 99,547,000	$ 111,898,000	$ 108,959,000	$ 104,280,000	$ 106,275,000	$ 111,336,000	$ 109,024,000	$ 111,249,000	$ 424,683,939	$ 437,883,097	$ 406,791,922
Earnings Per Share (Basic) (in dollars per share)	$ 0.39	$ 0.44	$ 0.42	$ 0.40	$ 0.41	$ 0.42	$ 0.40	$ 0.40	$ 1.67	$ 1.64	$ 1.42
Earnings Per Share (Diluted) (in dollars per share)	$ 0.39	$ 0.44	$ 0.42	$ 0.40	$ 0.41	$ 0.42	$ 0.40	$ 0.40	$ 1.66	$ 1.62	$ 1.41

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(21))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=117326831&loc=SL5780133-109256

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Comprehensive Income (AOCI Rollforward) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 1,861,751,660	$ 2,049,518,261	$ 1,910,424,234
Other comprehensive income (loss), net of tax	311,235	(2,150,994)	8,464,688
Ending balance	1,938,087,820	1,861,751,660	2,049,518,261
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,600,338)	7,193,383	(1,271,305)
Ending balance	(1,289,103)	(1,600,338)	7,193,383
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,674,887)	645,030	(2,862,999)
Other comprehensive income before reclassifications	(709,702)	(2,319,917)	3,508,029
Other comprehensive income (loss), net of tax	(709,702)	(2,319,917)	3,508,029
Ending balance	(2,384,589)	(1,674,887)	645,030
Unrealized gains(losses) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	74,549	6,626,379	2,788,975
ASU 2016-01 adoption impact	0	(6,642,727)	0
Other comprehensive income before reclassifications	1,403,521	1,675,823	4,444,360
Amounts reclassified from accumulated other comprehensive income	(382,584)	(1,584,926)	(606,956)
Other comprehensive income (loss), net of tax	1,020,937	(6,551,830)	3,837,404
Ending balance	1,095,486	74,549	6,626,379
Unrealized gains (losses) on derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	0	(78,026)	(1,197,281)
Other comprehensive income before reclassifications	0	175,308	248,042
Amounts reclassified from accumulated other comprehensive income	0	(97,282)	871,213
Other comprehensive income (loss), net of tax	0	78,026	1,119,255
Ending balance	$ 0	$ 0	$ (78,026)

Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes									$ (75,731,395)	$ (84,163,850)	$ (125,004,782)
Total reclassifications for the period	$ 99,547,000	$ 111,898,000	$ 108,959,000	$ 104,280,000	$ 106,275,000	$ 111,336,000	$ 109,024,000	$ 111,249,000	424,683,939	437,883,097	406,791,922
Amounts Reclassified from Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period									382,584	1,682,208	(264,257)
Amounts Reclassified from Other Comprehensive Income \| Unrealized gains on available-for-sale debt securities
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss)									484,283	2,006,235	933,778
Provision for income taxes									(101,699)	(421,309)	(326,822)
Total reclassifications for the period									382,584	1,584,926	606,956
Amounts Reclassified from Other Comprehensive Income \| Unrealized gains (losses) on derivatives
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss)									0	123,142	(1,340,329)
Provision for income taxes									0	(25,860)	469,116
Total reclassifications for the period									$ 0	$ 97,282	$ (871,213)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Goodwill and Other Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2013
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Goodwill	$ 307,365,845	$ 307,365,845
Amortization expense	22,400,000	22,500,000	$ 22,500,000
Patents and Other Intangible Assets
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Accumulated amortization	$ 143,100,000	122,300,000
Finite-lived intangible asset, useful life	10 years
Amortization expense, 2020	$ 22,000,000
Amortization expense, 2021	22,000,000
Amortization expense, 2022	21,000,000
Amortization expense, 2023	19,000,000
Amortization expense, 2024	16,000,000
HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Goodwill				$ 307,400,000
Accumulated amortization	$ 120,625,000	$ 101,325,000

Goodwill and Other Intangible Assets (Schedule of Goodwill) (Details)	12 Months Ended
	Dec. 31, 2019 USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2018	$ 307,365,845
Acquisitions	0
Divestitures	0
Impairments	0
Other	0
Balance as of December 31, 2019	$ 307,365,845

Goodwill and Other Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 250,375,000	$ 269,675,000
HomeLink®
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	(120,625,000)	(101,325,000)
Intangible assets, gross	371,000,000	371,000,000
Intangible assets, net	250,375,000	269,675,000
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	(93,750,000)	(78,750,000)
Finite-lived intangible assets, net	$ 86,250,000	$ 101,250,000
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	(26,875,000)	(22,575,000)
Finite-lived intangible assets, net	$ 16,125,000	$ 20,425,000
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

Revenue (Details) - USD ($)	3 Months Ended								12 Months Ended
Revenue (Details) - USD ($)	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 443,836,000	$ 477,761,000	$ 468,711,000	$ 468,589,000	$ 453,409,000	$ 460,253,000	$ 454,981,000	$ 465,420,000	$ 1,858,897,406	$ 1,834,063,697	$ 1,794,872,578
Automotive Segment
Disaggregation of Revenue [Line Items]
Revenues									1,810,536,887	1,791,198,296
Other
Disaggregation of Revenue [Line Items]
Revenues									48,360,519	42,865,401
Automotive Products
Disaggregation of Revenue [Line Items]
Revenues									1,810,536,887	1,791,198,296	1,758,127,468
Automotive Mirrors & Electronics \| Automotive Segment
Disaggregation of Revenue [Line Items]
Revenues									$ 1,638,600,272	1,598,589,777
Automotive Mirrors & Electronics \| Automotive Segment \| Minimum
Disaggregation of Revenue [Line Items]
Payment terms									15 days
Automotive Mirrors & Electronics \| Automotive Segment \| Maximum
Disaggregation of Revenue [Line Items]
Payment terms									90 days
HomeLink Modules \| Automotive Segment
Disaggregation of Revenue [Line Items]
Revenues									$ 171,936,615	192,608,519
Other Products (U.S.) \| Other
Disaggregation of Revenue [Line Items]
Revenues									48,360,519	42,865,401	36,745,110
Fire Protection Products \| Other
Disaggregation of Revenue [Line Items]
Revenues									$ 23,740,261	22,109,784
Fire Protection Products \| Other \| Minimum
Disaggregation of Revenue [Line Items]
Payment terms									30 days
Fire Protection Products \| Other \| Maximum
Disaggregation of Revenue [Line Items]
Payment terms									75 days
Windows Products \| Other
Disaggregation of Revenue [Line Items]
Revenues									$ 24,620,258	20,755,617
Dimmable Aircraft Windows \| Other \| Minimum
Disaggregation of Revenue [Line Items]
Payment terms									30 days
Dimmable Aircraft Windows \| Other \| Maximum
Disaggregation of Revenue [Line Items]
Payment terms									45 days
United States \| Automotive Products
Disaggregation of Revenue [Line Items]
Revenues									$ 569,939,756	583,672,971	567,492,812
United States \| Other Products (U.S.)
Disaggregation of Revenue [Line Items]
Revenues									48,360,519	42,865,401	36,745,110
Germany \| Automotive Products
Disaggregation of Revenue [Line Items]
Revenues									296,276,971	333,002,878	351,123,204
Japan \| Automotive Products
Disaggregation of Revenue [Line Items]
Revenues									225,577,146	209,311,790	185,261,067
Mexico \| Automotive Products
Disaggregation of Revenue [Line Items]
Revenues									160,967,900	106,111,515	93,603,796
Other Countries \| Automotive Products
Disaggregation of Revenue [Line Items]
Revenues									$ 557,775,114	$ 559,099,142	$ 560,646,589