Income Taxes - Net deferred tax assets (liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Employee compensation	$ 9.2	$ 9.0
Revenue recognition	32.8	34.3
Other	5.9	16.8
Deferred tax assets	47.9	60.1
Valuation allowance	(1.5)	(0.4)
Total deferred tax assets after valuation allowance	46.4	59.7
Recognition of franchise and equipment sales	(13.7)	(16.8)
Capitalization and depreciation (1)	(130.8)	(139.2)
Acquisition financing costs	0.0	(0.6)
Basis of property and equipment	0.0	(8.1)
Other	(0.4)	(0.8)
Deferred tax liabilities	(144.9)	(165.5)
Net deferred tax liabilities	$ (98.5)	$ (105.8)