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Segment Reporting (Schedule Of Automotive And Other Segment Reporting) (Details) - USD ($) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Segment Reporting Information [Line Items] |  |  |  |
Revenue | $ 454,981,440 | $ 443,139,073 | $ 920,401,545 | $ 896,674,323
Income from operations | 126,683,004 | 125,864,514 | 255,198,337 | 260,291,634
Automotive Products |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenue | 444,245,425 | 433,922,260 | 899,210,798 | 879,574,835
Income from operations | 123,758,195 | 123,222,811 | 248,720,353 | 255,727,768
Other |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenue | 10,736,015 | 9,216,813 | 21,190,747 | 17,099,488
Income from operations | $ 2,924,809 | $ 2,641,703 | $ 6,477,984 | $ 4,563,866

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