Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Revenue	$ 438,627,786	$ 429,643,276	$ 1,335,302,109	$ 1,259,011,840
Income from operations	129,072,652	134,212,281	389,364,286	383,806,992
Automotive Products
Segment Reporting Information [Line Items]
Revenue	428,161,863	419,793,577	1,307,736,698	1,228,165,639
Income from operations	125,817,994	130,567,201	381,545,762	372,119,627
Other
Segment Reporting Information [Line Items]
Revenue	10,465,923	9,849,699	27,565,411	30,846,201
Income from operations	$ 3,254,658	$ 3,645,080	$ 7,818,524	$ 11,687,365