Segment Reporting (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Net sales	$ 827,729	$ 586,221	$ 2,013,164	$ 1,807,461
OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	642,054	511,550	1,542,223	1,596,698
Travel trailers and fifth-wheels
Disaggregation of Revenue [Line Items]
Net sales	417,050	314,056	936,676	973,978
Motorhomes
Disaggregation of Revenue [Line Items]
Net sales	44,441	34,810	107,241	121,167
Adjacent industries OEMs
Disaggregation of Revenue [Line Items]
Net sales	180,563	162,684	498,306	501,553
Aftermarket Segment
Disaggregation of Revenue [Line Items]
Net sales	185,675	74,671	470,941	210,763
Chassis, chassis parts and slide-out mechanisms | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	253,182	193,354	586,985	610,946
Windows and doors | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	173,102	145,360	438,829	453,343
Furniture and mattresses | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	105,226	79,512	250,068	264,431
Axles and suspension solutions | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	42,708	31,405	103,450	97,597
Other | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	67,836	61,919	162,891	170,381
U.S.
Disaggregation of Revenue [Line Items]
Net sales	768,274	550,938	1,848,796	1,707,086
U.S. | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	588,764	480,654	1,392,997	1,507,400
U.S. | Travel trailers and fifth-wheels
Disaggregation of Revenue [Line Items]
Net sales	407,485	311,446	916,144	964,838
U.S. | Motorhomes
Disaggregation of Revenue [Line Items]
Net sales	29,707	25,944	70,126	86,808
U.S. | Adjacent industries OEMs
Disaggregation of Revenue [Line Items]
Net sales	151,572	143,264	406,727	455,754
U.S. | Aftermarket Segment
Disaggregation of Revenue [Line Items]
Net sales	179,510	70,284	455,799	199,686
International
Disaggregation of Revenue [Line Items]
Net sales	59,455	35,283	164,368	100,375
International | OEM Segment
Disaggregation of Revenue [Line Items]
Net sales	53,290	30,896	149,226	89,298
International | Travel trailers and fifth-wheels
Disaggregation of Revenue [Line Items]
Net sales	9,565	2,610	20,532	9,140
International | Motorhomes
Disaggregation of Revenue [Line Items]
Net sales	14,734	8,866	37,115	34,359
International | Adjacent industries OEMs
Disaggregation of Revenue [Line Items]
Net sales	28,991	19,420	91,579	45,799
International | Aftermarket Segment
Disaggregation of Revenue [Line Items]
Net sales	$ 6,165	$ 4,387	$ 15,142	$ 11,077