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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%

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- Definition Defined Benefit Plan, Impact of Decrease in Discount Rate on Earnings before Income Taxes + References No definition available. + Details
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- Definition Defined Benefit Plan, Impact of Decrease in Long-term Rate of Return on Assets + References No definition available. + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Description of assumption used to determine benefit obligation and net periodic benefit cost of defined benefit plan. Includes, but is not limited to, discount rate, rate of compensation increase, expected long-term rate of return on plan assets and interest crediting rate. + References No definition available. + Details
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