Nature of Operations and Summary of Significant Accounting Policies (Summary of Number of Restaurants) (Details) - restaurant	Sep. 27, 2020	Sep. 29, 2019	Sep. 30, 2018
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	2,241	2,243	2,237
Company-operated
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	144	137	137
Franchise
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	2,097	2,106	2,100