Franchise Operating Rights & Goodwill - Franchise Operating Rights and Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2019	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Franchise operating rights
Balance at the beginning of the period		$ 952.4	$ 809.2	$ 952.4
Impairment			(9.7)	(143.2)	$ (14.1)
Balance at the end of the period	$ 799.5		799.5	809.2	952.4
Goodwill
Balance at the beginning of the period		481.9	408.8	481.9
Impairment				(73.1)	(133.3)
Balance at the end of the period	408.8		408.8	408.8	481.9
Franchise operating rights and goodwill
Balance at the beginning of the period		1,434.3	1,218.0	1,434.3
Impairment	(9.7)	$ (216.3)	(9.7)	(216.3)	(147.4)
Balance at the end of the period	$ 1,208.3		$ 1,208.3	$ 1,218.0	$ 1,434.3

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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