Goodwill And Intangible Assets, Net (Summary of Goodwill and Intangible Assets, Net) (Details) - USD ($) $ in Millions		Jun. 30, 2020		Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	[1]	$ 1,181.3	[2]	$ 1,501.9
Franchise rights - indefinite-lived		509.0		566.5
Other intangibles		21.2		23.4
Other intangible assets, gross		530.2		589.9
Less: accumulated amortization		(8.2)		(8.3)
Other intangible assets, net		$ 522.0		$ 581.6

[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] Net of accumulated impairment losses of $257.4 million associated with our Premium Luxury reporting unit, $41.6 million associated with our Collision Centers reporting unit, and $19.3 million associated with our Parts Centers reporting unit, each of which were recorded during the three months ended March 31, 2020.