Goodwill And Intangible Assets, Net (Summary of Goodwill and Intangible Assets, Net) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 1,184.8	$ 1,185.0
Franchise rights - indefinite-lived	509.0	509.0
Other intangibles	19.6	19.6
Other intangible assets, gross	528.6	528.6
Less: accumulated amortization	(7.4)	(7.1)
Other intangible assets, net	$ 521.2	$ 521.5