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Employee Benefits - Single-Employer Defined Benefit Pension Plan - Narrative (Details) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 USD ($) | Dec. 30, 2017 USD ($) payment | Dec. 31, 2016 USD ($) | Jan. 02, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Unfunded status |  | $ 30,360 | $ 34,349 |
Gain (loss) adjustment to other comprehensive income (loss) net of tax |  | 100 | (2,100) | $ 400
Decrease in the unfunded obligation |  | 4,000 |  |
Actuarial loss |  | 5,808 | 2,094 |
Actual return on plan assets |  | 11,109 | 4,868 |
Employer contributions |  | 3,674 | 5,384 |
Charge due to current year service and interest cost |  | 5,300 |  |
Net periodic pension costs |  | 186 | (799) | $ (730)
Defined benefit plan, settlement, plan assets |  |  | 4,300 |
Estimated net loss expected to be amortized from accumulated other comprehensive loss into net periodic cost over the next fiscal year |  | 1,000 |  |
Accumulated benefit obligation for the hourly pension plan |  | $ 118,200 | $ 112,300 |
Expected return on plan assets assumption (percent) |  | 8.10% | 7.82% |
Number of minimum quarterly cash contributions during fiscal 2016 and 2017 | payment |  | 4 |  |
Minimum required contribution for plan year, per quarter cash contributions during fiscal - 2016 |  | $ 4,300 |  |
Scenario, Forecast |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Expected decrease in pension expense in future period | $ 400 |  |  |
Expected return on plan assets assumption (percent) | 6.00% |  |  |

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- Definition Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64852052&loc=d3e1703-114919 + Details
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