Goodwill And Intangible Assets, Net (Summary of Goodwill and Intangible Assets, Net) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Franchise rights - indefinite-lived	$ 575.3	$ 509.0
Other intangibles	19.5	19.6
Other intangible assets, gross	594.8	528.6
Less: accumulated amortization	(7.7)	(7.1)
Other intangible assets, net	587.1	521.5
Goodwill	$ 1,224.0	$ 1,185.0