Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Inventory [Line Items]
Inventory, Gross	$ 1,745,731	$ 1,563,067
Summary of inventories
Lower of cost or market reserves	(7,980)	(6,362)
New vehicles [Member]
Inventory [Line Items]
Inventory, Gross	1,262,797	1,137,478
Used vehicles [Member]
Inventory [Line Items]
Inventory, Gross	275,508	254,939
Rental vehicles [Member]
Inventory [Line Items]
Inventory, Gross	134,509	103,184
Parts, accessories and other [Member]
Inventory [Line Items]
Inventory, Gross	$ 72,917	$ 67,466