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Segment Reporting (Schedule of Automotive and Other Segment Reporting) (Details) - USD ($) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenues | $ 453,409,000 | $ 460,253,000 | $ 454,981,000 | $ 465,420,000 | $ 459,570,000 | $ 438,628,000 | $ 443,139,000 | $ 453,535,000 | $ 1,834,063,697 | $ 1,794,872,578 | $ 1,678,924,756
Income (Loss) from Operations | 125,499,000 | $ 127,428,000 | $ 126,683,000 | $ 128,515,000 | 133,994,000 | $ 129,073,000 | $ 125,865,000 | $ 134,427,000 | 508,125,547 | 523,358,352 | 511,742,935
Assets | 2,085,434,068 |  |  |  | 2,352,053,912 |  |  |  | 2,085,434,068 | 2,352,053,912 | 2,309,619,833
Depreciation & Amortization |  |  |  |  |  |  |  |  | 102,186,814 | 99,570,908 | 88,587,430
Capital Expenditures |  |  |  |  |  |  |  |  | 85,990,570 | 104,040,919 | 120,955,614
Corporate |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Assets | 621,190,035 |  |  |  | 870,415,748 |  |  |  | 621,190,035 | 870,415,748 | 842,246,344
Depreciation & Amortization |  |  |  |  |  |  |  |  | 4,484,918 | 3,891,873 | 1,729,886
Capital Expenditures |  |  |  |  |  |  |  |  | 205,621 | 21,166,986 | 20,944,269
Automotive Products |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  | 1,791,198,296 | 1,758,127,468 | 1,639,692,243
Income (Loss) from Operations |  |  |  |  |  |  |  |  | 495,471,799 | 512,895,699 | 497,753,966
Automotive Products | Operating Segments |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Assets | 1,449,910,935 |  |  |  | 1,472,061,650 |  |  |  | 1,449,910,935 | 1,472,061,650 | 1,457,989,335
Depreciation & Amortization |  |  |  |  |  |  |  |  | 97,279,052 | 95,378,100 | 86,567,248
Capital Expenditures |  |  |  |  |  |  |  |  | 84,337,455 | 82,703,576 | 99,811,083
Other |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  | 42,865,401 | 36,745,110 | 39,232,514
Income (Loss) from Operations |  |  |  |  |  |  |  |  | 12,653,748 | 10,462,653 | 13,988,969
Other | Operating Segments |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Assets | $ 14,333,098 |  |  |  | $ 9,576,514 |  |  |  | 14,333,098 | 9,576,514 | 9,384,154
Depreciation & Amortization |  |  |  |  |  |  |  |  | 422,844 | 300,935 | 290,296
Capital Expenditures |  |  |  |  |  |  |  |  | 1,447,494 | 170,357 | 200,262
U.S. | Automotive Products |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  | 583,672,971 | 567,492,812 | 554,945,912
Germany | Automotive Products |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  | 333,002,878 | 351,123,204 | 328,208,190
Japan | Automotive Products |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  | 209,311,790 | 185,261,067 | 154,005,299
Other | Automotive Products |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  | $ 665,210,657 | $ 654,250,385 | $ 602,532,841

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