Segment Reporting (Schedule of Automotive and Other Segment Reporting) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Revenues	$ 326,770,000	$ 288,622,000	$ 286,974,000	$ 269,499,000	$ 260,349,000	$ 268,248,000	$ 280,256,000	$ 290,707,000	$ 1,171,864,171	$ 1,099,559,521	$ 1,023,762,049
Income (Loss) from Operations	95,636,000	73,656,000	71,596,000	63,854,000	53,819,000	57,623,000	57,512,000	65,501,000	304,741,813	234,455,232	231,367,925
Assets	1,764,088,434				1,265,691,335				1,764,088,434	1,265,691,335	1,176,027,002
Depreciation & Amortization									62,854,155	50,179,823	42,634,684
Capital Expenditures									55,380,457	117,474,449	120,177,730
Automotive Products
Segment Reporting Information [Line Items]
Income (Loss) from Operations									298,465,299	231,713,972	231,030,145
Assets	1,290,801,674				619,337,527				1,290,801,674	619,337,527	566,395,900
Depreciation & Amortization									58,723,222	47,976,800	40,314,620
Capital Expenditures									54,020,792	113,611,526	115,377,859
Other
Segment Reporting Information [Line Items]
Revenues									27,876,044	22,586,580	20,600,687
Income (Loss) from Operations									6,276,514	2,741,260	337,780
Assets	9,001,278				8,010,779				9,001,278	8,010,779	8,993,853
Depreciation & Amortization									316,836	317,534	320,900
Capital Expenditures									301,697	228,635	58,996
Corporate
Segment Reporting Information [Line Items]
Assets	464,285,482				638,343,029				464,285,482	638,343,029	600,637,249
Depreciation & Amortization									3,814,097	1,885,489	1,999,164
Capital Expenditures									1,057,968	3,634,288	4,740,875
United States | Automotive Products
Segment Reporting Information [Line Items]
Revenues									400,654,021	382,308,501	334,692,637
Germany | Automotive Products
Segment Reporting Information [Line Items]
Revenues									244,949,664	239,081,723	248,495,295
Japan | Automotive Products
Segment Reporting Information [Line Items]
Revenues									123,884,470	100,422,507	76,123,221
Other | Automotive Products
Segment Reporting Information [Line Items]
Revenues									$ 374,499,972	$ 355,160,210	$ 343,850,209