Segment Reporting (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Net sales	$ 1,000,258	$ 659,670
OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	816,250	532,357
Travel trailers and fifth-wheels
Disaggregation of Revenue [Line Items]
Net sales	503,016	307,108
Motorhomes
Disaggregation of Revenue [Line Items]
Net sales	62,593	38,087
Adjacent industries OEMs
Disaggregation of Revenue [Line Items]
Net sales	250,641	187,162
Aftermarket Segment
Disaggregation of Revenue [Line Items]
Net sales	184,008	127,313
Chassis, chassis parts and slide-out mechanisms | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	287,061	202,263
Windows and doors | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	249,920	156,031
Furniture and mattresses | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	155,244	87,180
Axles and suspension solutions | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	55,122	35,136
Other | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	68,903	51,747
U.S.
Disaggregation of Revenue [Line Items]
Net sales	909,051	598,815
U.S. | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	737,641	477,197
U.S. | Travel trailers and fifth-wheels
Disaggregation of Revenue [Line Items]
Net sales	486,542	303,682
U.S. | Motorhomes
Disaggregation of Revenue [Line Items]
Net sales	39,417	26,914
U.S. | Adjacent industries OEMs
Disaggregation of Revenue [Line Items]
Net sales	211,682	146,601
U.S. | Aftermarket Segment
Disaggregation of Revenue [Line Items]
Net sales	171,410	121,618
International
Disaggregation of Revenue [Line Items]
Net sales	91,207	60,855
International | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	78,609	55,160
International | Travel trailers and fifth-wheels
Disaggregation of Revenue [Line Items]
Net sales	16,474	3,426
International | Motorhomes
Disaggregation of Revenue [Line Items]
Net sales	23,176	11,173
International | Adjacent industries OEMs
Disaggregation of Revenue [Line Items]
Net sales	38,959	40,561
International | Aftermarket Segment
Disaggregation of Revenue [Line Items]
Net sales	$ 12,598	$ 5,695