Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Revenue	$ 443,139,073	$ 423,800,778	$ 896,674,323	$ 829,368,564
Income from operations	125,864,514	128,745,721	260,291,634	249,594,711
Automotive Products
Segment Reporting Information [Line Items]
Revenue	433,922,260	414,403,115	879,574,835	808,372,062
Income from operations	123,222,811	125,571,809	255,727,768	241,552,426
Other
Segment Reporting Information [Line Items]
Revenue	9,216,813	9,397,663	17,099,488	20,996,502
Income from operations	$ 2,641,703	$ 3,173,912	$ 4,563,866	$ 8,042,285