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Fair Value of Assets and Liabilities - Assets Measured at Fair Value (Details) - USD ($) $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 29, 2019 | Jun. 30, 2018 | Dec. 29, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Impairment charges | $ 0 | $ 1,125 |
Investments in equity securities | 11,161 |  | $ 10,312
Mutual funds | 9,619 |  | 9,112
Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Investments in equity securities | 11,161 |  | 10,312
Mutual funds | 9,619 |  | 9,112
Significant Other Observable Inputs (Level 2) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Investments in equity securities | 0 |  | 0
Mutual funds | 0 |  | 0
Significant Unobservable Inputs (Level 3) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Investments in equity securities | 0 |  | 0
Mutual funds | 0 |  | $ 0
Other Expense (Income) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Impairment charges | 2,800 |  |
Investments in equity securities | $ 1,200 |  |

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