Segment Reporting (Schedule of Net Sales by Product) (Details) - USD ($) $ in Thousands	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
Total net sales	$ 536,616	$ 604,244	$ 684,455	$ 650,492	$ 547,137	$ 554,814	$ 547,483	$ 498,336	$ 2,475,807	$ 2,147,770	$ 1,678,898
OEM Segment
Segment Reporting Information
Total net sales									2,242,616	1,976,623	1,548,091
Aftermarket Segment
Segment Reporting Information
Total net sales									233,191	171,147	130,807
Chassis, Chassis Parts and Slide-out Mechanisms | OEM Segment
Segment Reporting Information
Total net sales									908,065	914,397	743,160
Windows and Doors | OEM Segment
Segment Reporting Information
Total net sales									615,644	424,625	335,717
Furniture and Mattresses | OEM Segment
Segment Reporting Information
Total net sales									380,514	342,680	245,596
Axles and Suspension Solutions | OEM Segment
Segment Reporting Information
Total net sales									122,897	123,513	115,538
Other Products | OEM Segment
Segment Reporting Information
Total net sales									$ 215,496	$ 171,408	$ 108,080