Segment Reporting (Schedule of Operating Profit by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information
Operating profit	$ 101,431	$ 44,266
Operating Segments \| OEM Segment
Segment Reporting Information
Operating profit	79,287	43,189
Operating Segments \| Aftermarket Segment
Segment Reporting Information
Operating profit	$ 22,144	$ 1,077

The net result for the period of deducting operating expenses from operating revenues.

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