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Benefit Plans - The Company's Pension Plan Assets Measured at Fair Value (Details) - USD ($) $ in Thousands | Dec. 26, 2020 | Dec. 28, 2019
--- | --- | ---
Defined Benefit Plan Disclosure |  |
Total pension plan assets | $ 100,478 | $ 78,502
Insurance contracts and other |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 2,565 | 756
Cash and cash equivalents |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 4,522 | 565
Equity securities |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 8,623 | 20,935
Fixed income |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 31,675 | 56,246
Bulk annuity contract |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 53,093 |
Level 1 |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 8,537 | 6,718
Level 1 | Insurance contracts and other |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 0 | 0
Level 1 | Cash and cash equivalents |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 654 | 387
Level 1 | Equity securities |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 1,719 | 1,796
Level 1 | Fixed income |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 6,164 | 4,535
Level 1 | Bulk annuity contract |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 0 |
Level 2 |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 32,085 | 0
Level 2 | Insurance contracts and other |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 1,880 | 0
Level 2 | Cash and cash equivalents |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 3,868 | 0
Level 2 | Equity securities |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 6,904 | 0
Level 2 | Fixed income |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 19,433 | 0
Level 2 | Bulk annuity contract |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 0 |
Level 3 |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 53,778 | 609
Level 3 | Insurance contracts and other |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 685 | 609
Level 3 | Cash and cash equivalents |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 0 | 0
Level 3 | Equity securities |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 0 | 0
Level 3 | Fixed income |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 0 | 0
Level 3 | Bulk annuity contract |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 53,093 |
NAV |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 6,078 | 71,175
NAV | Insurance contracts and other |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 0 | 147
NAV | Cash and cash equivalents |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 0 | 178
NAV | Equity securities |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 0 | 19,139
NAV | Fixed income |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | 6,078 | $ 51,711
NAV | Bulk annuity contract |  |
Defined Benefit Plan Disclosure |  |
Total pension plan assets | $ 0 |

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- Definition Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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