Description of Business and Summary of Significant Accounting Policies (Goodwill and Other Intangible Assets) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Intangible Assets [Line Items]
Franchise agreements, minimal contractual terms (in years)			1 year
Goodwill impairment			$ 318,300,000	$ 0	$ 0
Franchise rights impairment			$ 57,500,000	9,600,000	8,100,000
Minimum [Member]
Goodwill and Intangible Assets [Line Items]
Other intangibles, useful life			3 years
Maximum [Member]
Goodwill and Intangible Assets [Line Items]
Other intangibles, useful life			30 years
Nonrecurring [Member]
Goodwill and Intangible Assets [Line Items]
Goodwill impairment		$ 318,300,000	$ 318,300,000	0
Nonrecurring [Member] | Franchise Rights [Member]
Goodwill and Intangible Assets [Line Items]
Franchise rights impairment	$ 0	$ 57,500,000		$ 9,600,000	$ 8,100,000