Fair Value of Assets and Liabilities - Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 26, 2020	Dec. 28, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash Equivalents	$ 73,461	$ 118,999
Investments in equity securities	19,186	12,969
Mutual funds	13,249	10,464
Total	105,896	142,432
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash Equivalents	73,461	118,999
Investments in equity securities	19,186	12,969
Mutual funds	13,249	10,464
Total	105,896	142,432
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash Equivalents	0	0
Investments in equity securities	0	0
Mutual funds	0	0
Total	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash Equivalents	0	0
Investments in equity securities	0	0
Mutual funds	0	0
Total	$ 0	$ 0