Significant Accounting Policies - Stock-Based Compensation, PP&E, and Deferred Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 25, 2016	Dec. 27, 2015
Stock-Based Compensation
Vesting period	3 years
Property and Equipment
Depreciation expense	$ 42.6	$ 39.7	$ 39.7
Deferred Costs
Deferred costs, maximum amortization period	5 years
Deferred costs	$ 4.1	2.9	$ 2.6
Unamortized systems development costs	$ 11.1	$ 9.8
Restaurant, commissary and other equipment | Minimum
Property and Equipment
Estimated useful lives	5 years
Restaurant, commissary and other equipment | Maximum
Property and Equipment
Estimated useful lives	10 years
Buildings and improvements | Minimum
Property and Equipment
Estimated useful lives	20 years
Buildings and improvements | Maximum
Property and Equipment
Estimated useful lives	40 years
Technology and communication assets
Property and Equipment
Estimated useful lives	5 years
Leasehold improvements | Minimum
Property and Equipment
Estimated useful lives	5 years
Leasehold improvements | Maximum
Property and Equipment
Estimated useful lives	10 years