Franchise Operating Rights & Goodwill - Franchise Operating Rights and Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Franchise operating rights
Balance at the beginning of the period	$ 799.5	$ 809.2
Impairment	(14.0)	(9.7)	$ (143.2)
Balance at the end of the period	785.5	799.5	809.2
Goodwill
Balance at the beginning of the period	408.8	408.8
Impairment	0.0	0.0	(73.1)
Balance at the end of the period	408.8	408.8	408.8
Franchise operating rights and goodwill
Balance at the beginning of the period	1,208.3	1,218.0
Impairment	(14.0)	(9.7)	(216.3)
Balance at the end of the period	$ 1,194.3	$ 1,208.3	$ 1,218.0