Segment Reporting (Schedule of Operating Profit by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information
Operating profit	$ 93,982	$ 20,782	$ 195,413	$ 65,048
Operating Segments | OEM Segment
Segment Reporting Information
Operating profit	63,334	1,763	142,621	44,952
Operating Segments | Aftermarket Segment
Segment Reporting Information
Operating profit	$ 30,648	$ 19,019	$ 52,792	$ 20,096