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Retirement Plans (Fair Values of Qualified Plan's Assets) (Details) - USD ($) $ in Thousands | Sep. 29, 2019 | Sep. 30, 2018
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | $ 476,194 |  | $ 456,127
Cash and cash equivalents |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | 10,110 |  | 2,901
Domestic Equities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | 99,124 |  | 104,424
International equity |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | 94,953 |  | 100,340
Investment grade |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | 177,500 |  | 160,106
High yield |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | 9,256 |  | 14,384
Alternatives |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | 42,052 |  | 35,964
Real estate |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | 43,199 |  | 38,008
Quoted Prices in Active Markets for Identical (Level 1) |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | 155,642 |  | 168,665
Quoted Prices in Active Markets for Identical (Level 1) | Cash and cash equivalents |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [1] | 0 |  | 0
Quoted Prices in Active Markets for Identical (Level 1) | Domestic Equities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [2] | 99,124 |  | 104,424
Quoted Prices in Active Markets for Identical (Level 1) | International equity |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [3],[4] | 47,262 |  | 49,857
Quoted Prices in Active Markets for Identical (Level 1) | Investment grade |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [5] | 0 |  | 0
Quoted Prices in Active Markets for Identical (Level 1) | High yield |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [6] | 9,256 |  | 14,384
Quoted Prices in Active Markets for Identical (Level 1) | Alternatives |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [7] | 0 | [3] | 0
Quoted Prices in Active Markets for Identical (Level 1) | Real estate |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [3],[8] | 0 |  | 0
Significant Other Observable Inputs (Level 2) |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | 187,610 |  | 163,007
Significant Other Observable Inputs (Level 2) | Cash and cash equivalents |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [1] | 10,110 |  | 2,901
Significant Other Observable Inputs (Level 2) | Domestic Equities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [2] | 0 |  | 0
Significant Other Observable Inputs (Level 2) | International equity |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [3],[4] | 0 |  | 0
Significant Other Observable Inputs (Level 2) | Investment grade |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [5] | 177,500 |  | 160,106
Significant Other Observable Inputs (Level 2) | High yield |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [6] | 0 |  | 0
Significant Other Observable Inputs (Level 2) | Alternatives |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [7] | 0 | [3] | 0
Significant Other Observable Inputs (Level 2) | Real estate |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [3],[8] | 0 |  | 0
Significant Unobservable Inputs (Level 3) |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets |  | 0 |  | 0
Significant Unobservable Inputs (Level 3) | Cash and cash equivalents |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [1] | 0 |  | 0
Significant Unobservable Inputs (Level 3) | Domestic Equities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [2] | 0 |  | 0
Significant Unobservable Inputs (Level 3) | International equity |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [3],[4] | 0 |  | 0
Significant Unobservable Inputs (Level 3) | Investment grade |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [5] | 0 |  | 0
Significant Unobservable Inputs (Level 3) | High yield |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [6] | 0 |  | 0
Significant Unobservable Inputs (Level 3) | Alternatives |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [7] | 0 | [3] | 0
Significant Unobservable Inputs (Level 3) | Real estate |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of plan assets | [3],[8] | $ 0 |  | $ 0
[1] | Cash and cash equivalents are comprised of commercial paper, short-term bills and notes, and short-term investment funds, which are valued at quoted prices in active markets for similar securities.
[2] | U.S. equity securities are comprised of investments in common stock of U.S. companies for total return purposes. These investments are valued by the trustee at closing prices from national exchanges on the valuation date.
[3] | Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the statement of financial position.
[4] | International equity securities are comprised of investments in common stock of companies located outside of the U.S for total return purposes. These investments are valued by the trustee at closing prices from national exchanges on the valuation date, or the values are adjusted as a result of market movements following the close of local trading using inputs to models that are observable either directly or indirectly. The portion of these investments that are measured at fair value using the net asset value per share practical expedient (see note 4 below) can be redeemed on a monthly basis.
[5] | Investment grade fixed income consists of debt obligations either issued by the US government or have a rating of BBB- / Baa or higher assigned by a major credit rating agency. These investments are valued based on unadjusted quoted market prices (Level 1), or based on quoted prices in inactive markets, or whose values are based on models, but the inputs to those models are observable either directly or indirectly (Level 2).
[6] | High yield fixed income consists primarily of debt obligations that have a rating of below BBB- / Baa or lower assigned by a major credit rating agency. These investments are valued based on unadjusted quoted market prices.
[7] | Alternative investments consist primarily of an investment in asset classes other than stocks, bonds, and cash. Alternative investments can include commodities, hedge funds, private equity, managed futures, and derivatives. These investments are valued based on unadjusted quoted market prices and can be redeemed on a bi-monthly basis.
[8] | Real estate is investments in a real estate collective trust for purposes of total return. These investments are valued based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These investments can be redeemed on a quarterly basis.

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