Adoption of ASU 2014-09, "Revenue from Contracts with Customers" - Cumulative Effect Adjustments (Details) - Accounting Standards Update 2014-09 $ in Millions	Jan. 01, 2018 USD ($)
Retained Earnings Adjustments [Line Items]
Cumulative effect adjustment to retained earnings	$ (21.5)
Franchise royalties and fees
Retained Earnings Adjustments [Line Items]
Cumulative effect adjustment to retained earnings	(10.8)
Customer loyalty program
Retained Earnings Adjustments [Line Items]
Cumulative effect adjustment to retained earnings	(8.0)
Marketing funds
Retained Earnings Adjustments [Line Items]
Cumulative effect adjustment to retained earnings	$ (2.7)