Retirement Plans (Determining the Present Values of Benefit Obligations and Net Periodic Benefit Costs) (Details) $ in Millions	3 Months Ended		4 Months Ended	12 Months Ended
	Jul. 05, 2020	Apr. 12, 2020	Jan. 19, 2020	Sep. 27, 2020 USD ($) restaurant	Sep. 29, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Cash flow period extension				30
Increase in earnings before income taxes from 0.25% decrease in the discount rate				$ 0.1
Decrease in earnings before income taxes from 0.25% decrease in the long-term rate of return on assets				$ 1.0
Supplemental Employee Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Assumptions used to determine benefit obligations, Discount rate				2.84%	3.24%	4.37%
Assumptions used to determine benefit obligations, Rate of future pay increases					3.50%	3.50%
Assumptions used to determine net periodic benefit cost, Discount rate				3.24%	4.37%	3.80%
Assumptions used to determine net periodic benefit cost, Rate of future pay increases				3.50%	3.50%	3.50%
Number of active employees | restaurant				0
Postretirement Health Plans
Defined Benefit Plan Disclosure [Line Items]
Assumptions used to determine benefit obligations, Discount rate				2.77%	3.24%	4.38%
Assumptions used to determine net periodic benefit cost, Discount rate				3.24%	4.38%	3.82%
Qualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Assumptions used to determine benefit obligations, Discount rate				3.10%	3.36%	4.40%
Assumptions used to determine net periodic benefit cost, Discount rate	3.13%	3.38%	3.61%	3.36%	4.40%	3.99%
Assumptions used to determine net periodic benefit cost, Long-term rate of return on assets	5.40%	5.20%	5.90%	5.80%	5.85%	5.80%