Segments Information - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segments Information
Revenue	$ 1,474,347	$ 1,441,477	$ 2,539,116	$ 2,500,138
Intersegment Eliminations
Segments Information
Revenue	(13,223)	(14,177)	(24,035)	(24,521)
Good Sam services and plans
Segments Information
Revenue	44,694	42,338	91,660	87,163
Good Sam services and plans | Intersegment Eliminations
Segments Information
Revenue	(297)	(374)	(1,629)	(1,727)
New vehicles
Segments Information
Revenue	778,870	807,519	1,308,447	1,387,029
New vehicles | Intersegment Eliminations
Segments Information
Revenue	(1,826)	(1,747)	(2,998)	(2,911)
Used vehicles
Segments Information
Revenue	245,749	210,646	425,757	382,737
Used vehicles | Intersegment Eliminations
Segments Information
Revenue	(782)	(598)	(1,379)	(1,090)
Products, service and other
Segments Information
Revenue	264,426	250,359	469,302	414,511
Products, service and other | Intersegment Eliminations
Segments Information
Revenue	(7,045)	(8,075)	(12,367)	(12,891)
Finance and insurance, net
Segments Information
Revenue	128,225	120,205	220,116	209,305
Finance and insurance, net | Intersegment Eliminations
Segments Information
Revenue	(3,273)	(3,383)	(5,662)	(5,902)
Good Sam Club
Segments Information
Revenue	12,383	10,410	23,834	19,393
Good Sam services and plans | Operating Segments
Segments Information
Revenue	44,991	42,712	93,289	88,890
Good Sam services and plans | Good Sam services and plans | Operating Segments
Segments Information
Revenue	44,991	42,712	93,289	88,890
RV and Outdoor Retail
Segments Information
Revenue	1,429,653	1,399,139	2,447,456	2,412,975
RV and Outdoor Retail | Operating Segments
Segments Information
Revenue	1,442,579	1,412,942	2,469,862	2,435,769
RV and Outdoor Retail | New vehicles
Segments Information
Revenue	778,870	807,519	1,308,447	1,387,029
RV and Outdoor Retail | New vehicles | Operating Segments
Segments Information
Revenue	780,696	809,266	1,311,445	1,389,940
RV and Outdoor Retail | Used vehicles
Segments Information
Revenue	245,749	210,646	425,757	382,737
RV and Outdoor Retail | Used vehicles | Operating Segments
Segments Information
Revenue	246,531	211,244	427,136	383,827
RV and Outdoor Retail | Products, service and other
Segments Information
Revenue	264,426	250,359	469,302	414,511
RV and Outdoor Retail | Products, service and other | Operating Segments
Segments Information
Revenue	271,471	258,434	481,669	427,402
RV and Outdoor Retail | Finance and insurance, net
Segments Information
Revenue	128,225	120,205	220,116	209,305
RV and Outdoor Retail | Finance and insurance, net | Operating Segments
Segments Information
Revenue	131,498	123,588	225,778	215,207
RV and Outdoor Retail | Good Sam Club
Segments Information
Revenue	12,383	10,410	23,834	19,393
RV and Outdoor Retail | Good Sam Club | Operating Segments
Segments Information
Revenue	$ 12,383	$ 10,410	$ 23,834	$ 19,393