Segment Reporting (Schedule of Net Sales by Product) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information
Total net sales	$ 564,021	$ 586,221	$ 629,068	$ 592,172	$ 536,616	$ 604,244	$ 684,455	$ 650,492	$ 2,371,482	$ 2,475,807	$ 2,147,770
OEM Segment
Segment Reporting Information
Total net sales									2,091,901	2,242,616	1,976,623
Aftermarket Segment
Segment Reporting Information
Total net sales									279,581	233,191	171,147
Chassis, Chassis Parts and Slide-out Mechanisms | OEM Segment
Segment Reporting Information
Total net sales									796,434	908,065	914,397
Windows and Doors | OEM Segment
Segment Reporting Information
Total net sales									585,464	615,644	424,625
Furniture and Mattresses | OEM Segment
Segment Reporting Information
Total net sales									342,691	380,514	342,680
Axles and Suspension Solutions | OEM Segment
Segment Reporting Information
Total net sales									129,471	122,897	123,513
Other Products | OEM Segment
Segment Reporting Information
Total net sales									$ 237,841	$ 215,496	$ 171,408