Segment Reporting (Schedule of Automotive and Other Segment Reporting) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 405,593,000	$ 389,829,000	$ 379,258,000	$ 368,937,000	$ 350,411,000	$ 350,914,000	$ 338,437,000	$ 335,739,000	$ 1,543,617,706	$ 1,375,501,159	$ 1,171,864,171
Income (Loss) from Operations	126,662,000	$ 116,263,000	$ 108,133,000	$ 107,709,000	98,615,000	$ 103,206,000	$ 99,835,000	$ 97,178,000	458,766,439	398,834,174	304,741,813
Assets	2,148,672,928				2,022,540,029				2,148,672,928	2,022,540,029	1,764,088,434
Depreciation & Amortization									80,599,167	77,376,305	62,854,155
Capital Expenditures									97,941,762	72,518,987	55,380,457
Automotive Products
Segment Reporting Information [Line Items]
Revenues									1,506,872,004	1,340,122,274	1,143,988,127
Income (Loss) from Operations									445,067,511	386,762,986	298,465,299
Assets	1,414,426,679				1,333,615,389				1,414,426,679	1,333,615,389	1,290,801,674
Depreciation & Amortization									78,925,332	75,320,999	58,723,222
Capital Expenditures									97,632,519	71,032,115	54,020,792
Other
Segment Reporting Information [Line Items]
Revenues									36,745,702	35,378,885	27,876,044
Income (Loss) from Operations									13,698,928	12,071,188	6,276,514
Assets	9,429,994				8,841,958				9,429,994	8,841,958	9,001,278
Depreciation & Amortization									306,908	321,426	316,836
Capital Expenditures									161,247	145,704	301,697
Corporate
Segment Reporting Information [Line Items]
Assets	$ 724,816,255				$ 680,082,682				724,816,255	680,082,682	464,285,482
Depreciation & Amortization									1,366,927	1,733,880	3,814,097
Capital Expenditures									147,996	1,341,168	1,057,968
United States | Automotive Products
Segment Reporting Information [Line Items]
Revenues									494,876,354	444,921,897	400,654,021
Germany | Automotive Products
Segment Reporting Information [Line Items]
Revenues									295,044,988	262,505,346	244,949,664
Japan | Automotive Products
Segment Reporting Information [Line Items]
Revenues									148,632,237	133,758,799	123,884,470
Other | Automotive Products
Segment Reporting Information [Line Items]
Revenues									$ 568,318,425	$ 498,936,232	$ 374,499,972