Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Advertising Costs) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 26, 2018	Dec. 27, 2017	Dec. 28, 2016
Franchisor Disclosure
Advertising expense	$ 15.0	$ 14.3	$ 13.1
Advertising contributions from franchisees		79.7	76.5
Franchised Units [Member]
Franchisor Disclosure
Advertising expense	$ 78.3	$ 1.9	$ 1.9

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 720
-SubTopic 35
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848

Name:	us-gaap_AdvertisingExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration