Goodwill and Intangible Assets, Net (Goodwill) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill, beginning balance	[1]	$ 1,511.3		$ 1,394.5
Acquisitions, dispositions, and other adjustments, net		3.7	[2]	116.8
Goodwill, ending balance	[1]	1,515.0		1,511.3
Accumulated impairment losses		1,470.0		1,470.0	$ 1,470.0
Reporting Unit, Domestic [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	[1]	252.1		203.1
Acquisitions, dispositions, and other adjustments, net		(20.4)	[2]	49.0
Goodwill, ending balance	[1]	231.7		252.1
Accumulated impairment losses		140.0		140.0	$ 140.0
Reporting Unit, Import [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	[1]	558.2		570.9
Acquisitions, dispositions, and other adjustments, net		(25.8)	[2]	(12.7)
Goodwill, ending balance	[1]	532.4		558.2
Reporting Unit, Premium Luxury [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	[1]	697.4		620.5
Acquisitions, dispositions, and other adjustments, net		14.7	[2]	76.9
Goodwill, ending balance	[1]	712.1		697.4
Reporting Unit, Other [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	[1]	3.6		0.0
Acquisitions, dispositions, and other adjustments, net		35.2	[2]	3.6
Goodwill, ending balance	[1]	$ 38.8		$ 3.6

[1] Net of accumulated impairment losses of $1.47 billion associated with our single reporting unit (prior to September 30, 2008, our reporting unit structure was comprised of a single reporting unit) and $140.0 million associated with our Domestic reporting unit, both of which were recorded during the year ended December 31, 2008.

[2] Includes amounts reclassified to held for sale, which are presented in Other Current Assets in our Consolidated Balance Sheet as of December 31, 2017.