Segments Information - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segments Information
Revenue	$ 1,387,972	$ 1,309,486	$ 3,927,088	$ 3,809,624
Intersegment Eliminations
Segments Information
Revenue	(11,024)	(13,071)	(35,059)	(37,592)
Good Sam services and plans
Segments Information
Revenue	42,235	41,311	133,895	128,474
Good Sam services and plans | Intersegment Eliminations
Segments Information
Revenue	(226)	(182)	(1,855)	(1,909)
New vehicles
Segments Information
Revenue	680,716	697,317	1,989,163	2,084,346
New vehicles | Intersegment Eliminations
Segments Information
Revenue	(1,415)	(1,393)	(4,413)	(4,304)
Used vehicles
Segments Information
Revenue	247,151	197,757	672,908	580,494
Used vehicles | Intersegment Eliminations
Segments Information
Revenue	(556)	(571)	(1,935)	(1,661)
Products, service and other
Segments Information
Revenue	290,771	256,150	760,073	670,661
Products, service and other | Intersegment Eliminations
Segments Information
Revenue	(6,135)	(7,907)	(18,502)	(20,798)
Finance and insurance, net
Segments Information
Revenue	114,466	106,218	334,582	315,523
Finance and insurance, net | Intersegment Eliminations
Segments Information
Revenue	(2,692)	(3,018)	(8,354)	(8,920)
Good Sam Club
Segments Information
Revenue	12,633	10,733	36,467	30,126
Good Sam services and plans | Operating Segments
Segments Information
Revenue	42,461	41,493	135,750	130,383
Good Sam services and plans | Good Sam services and plans | Operating Segments
Segments Information
Revenue	42,461	41,493	135,750	130,383
RV and Outdoor Retail
Segments Information
Revenue	1,345,737	1,268,175	3,793,193	3,681,150
RV and Outdoor Retail | Operating Segments
Segments Information
Revenue	1,356,535	1,281,064	3,826,397	3,716,833
RV and Outdoor Retail | New vehicles
Segments Information
Revenue	680,716	697,317	1,989,163	2,084,346
RV and Outdoor Retail | New vehicles | Operating Segments
Segments Information
Revenue	682,131	698,710	1,993,576	2,088,650
RV and Outdoor Retail | Used vehicles
Segments Information
Revenue	247,151	197,757	672,908	580,494
RV and Outdoor Retail | Used vehicles | Operating Segments
Segments Information
Revenue	247,707	198,328	674,843	582,155
RV and Outdoor Retail | Products, service and other
Segments Information
Revenue	290,771	256,150	760,073	670,661
RV and Outdoor Retail | Products, service and other | Operating Segments
Segments Information
Revenue	296,906	264,057	778,575	691,459
RV and Outdoor Retail | Finance and insurance, net
Segments Information
Revenue	114,466	106,218	334,582	315,523
RV and Outdoor Retail | Finance and insurance, net | Operating Segments
Segments Information
Revenue	117,158	109,236	342,936	324,443
RV and Outdoor Retail | Good Sam Club
Segments Information
Revenue	12,633	10,733	36,467	30,126
RV and Outdoor Retail | Good Sam Club | Operating Segments
Segments Information
Revenue	$ 12,633	$ 10,733	$ 36,467	$ 30,126