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