Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Net Sales	$ 260,349,000	$ 268,248,000	$ 280,256,000	$ 290,707,000	$ 260,347,000	$ 269,468,000	$ 243,002,000	$ 250,946,000	$ 1,099,559,521	$ 1,023,762,049	$ 816,263,414
Income (Loss) From Operations	53,819,000	57,623,000	57,512,000	65,501,000	55,783,000	62,247,000	53,247,000	60,091,000	234,455,232	231,367,925	190,972,069
Assets	1,265,691,335				1,176,027,002				1,265,691,335	1,176,027,002	1,002,690,639
Depreciation & Amortization									50,179,823	42,634,684	38,620,674
Capital Expenditures									117,474,449	120,177,730	46,896,950
Automotive Products [Member]
Segment Reporting Information [Line Items]
Income (Loss) From Operations									231,713,972	231,030,145	191,430,183
Assets	619,337,527				566,395,900				619,337,527	566,395,900	391,514,600
Depreciation & Amortization									47,976,800	40,314,620	35,722,078
Capital Expenditures									113,611,526	115,377,859	43,031,399
Other [Member]
Segment Reporting Information [Line Items]
Net Sales									22,586,580	20,600,687	19,171,452
Income (Loss) From Operations									2,741,260	337,780	(458,114)
Assets	8,010,779				8,993,853				8,010,779	8,993,853	6,687,533
Depreciation & Amortization									317,534	320,900	275,599
Capital Expenditures									228,635	58,996	203,654
Corporate [Member]
Segment Reporting Information [Line Items]
Assets	638,343,029				600,637,249				638,343,029	600,637,249	604,488,506
Depreciation & Amortization									1,885,489	1,999,164	2,622,997
Capital Expenditures									3,634,288	4,740,875	3,661,897
United States [Member] | Automotive Products [Member]
Segment Reporting Information [Line Items]
Net Sales									382,308,501	334,692,637	274,165,934
Germany [Member] | Automotive Products [Member]
Segment Reporting Information [Line Items]
Net Sales									239,081,723	248,495,295	212,555,637
Japan [Member] | Automotive Products [Member]
Segment Reporting Information [Line Items]
Net Sales									100,422,507	76,123,221	64,412,780
Other Countries [Member] | Automotive Products [Member]
Segment Reporting Information [Line Items]
Net Sales									$ 355,160,210	$ 343,850,209	$ 245,957,611