Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting Information [Line Items]
Revenue	$ 1,023,762,049	$ 816,263,414	$ 544,522,993
Income (Loss) From Operations	231,367,925	190,972,069	94,619,069
Assets	1,176,027,002	1,002,690,639	822,603,489
Depreciation & Amortization	42,634,684	38,620,674	38,364,492
Capital Expenditure	120,177,730	46,896,950	21,130,500
Automotive Products [Member]
Segment Reporting Information [Line Items]
Income (Loss) From Operations	231,030,145	191,430,183	96,815,575
Assets	566,395,900	391,514,600	311,306,542
Depreciation & Amortization	40,314,620	35,722,078	34,960,303
Capital Expenditure	115,377,859	43,031,399	15,250,621
Other [Member]
Segment Reporting Information [Line Items]
Revenue	20,600,687	19,171,452	18,884,986
Income (Loss) From Operations	337,780	(458,114)	(2,196,506)
Assets	8,993,853	6,687,533	5,793,232
Depreciation & Amortization	320,900	275,599	243,734
Capital Expenditure	58,996	203,654	567,486
Corporate [Member]
Segment Reporting Information [Line Items]
Assets	600,637,249	604,488,506	505,503,715
Depreciation & Amortization	1,999,164	2,622,997	3,160,455
Capital Expenditure	4,740,875	3,661,897	5,312,393
United States [Member] | Automotive Products [Member]
Segment Reporting Information [Line Items]
Revenue	334,692,637	274,165,934	173,459,790
Germany [Member] | Automotive Products [Member]
Segment Reporting Information [Line Items]
Revenue	248,495,295	212,555,637	159,713,458
Japan [Member] | Automotive Products [Member]
Segment Reporting Information [Line Items]
Revenue	76,123,221	64,412,780	54,867,288
Other Countries [Member] | Automotive Products [Member]
Segment Reporting Information [Line Items]
Revenue	$ 343,850,209	$ 245,957,611	$ 137,597,471