Income Taxes - Net deferred tax assets (liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Lease liabilities	$ 93.6	$ 112.9
Employee compensation	9.7	12.1
Revenue recognition	37.1	35.4
Other	8.4	8.4
Deferred tax assets	148.8	168.8
Valuation allowance	(3.5)	(4.2)
Total deferred tax assets after valuation allowance	145.3	164.6
Recognition of franchise and equipment sales	(6.7)	(8.2)
Capitalization and depreciation	(121.0)	(122.7)
Lease assets	(90.8)	(108.6)
Other	(1.5)	(1.3)
Deferred tax liabilities	(220.0)	(240.8)
Net deferred tax liabilities	$ (74.7)	$ (76.2)