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