FAIR VALUE - Fair Value of Assets and Liabilities (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Jun. 26, 2021	Dec. 26, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 1,592	$ 2,273
Other assets:
Life insurance policies	40,652	35,770
Total assets measured at fair value	42,244	38,043
Other current liabilities measured at fair value:
Contingent consideration	23,531
Other long-term liabilities measured at fair value:
Contingent consideration	13,776	2,328
Total liabilities measured at fair value	37,307	2,328
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Other assets:
Life insurance policies	0	0
Total assets measured at fair value	0	0
Other current liabilities measured at fair value:
Contingent consideration	0
Other long-term liabilities measured at fair value:
Contingent consideration	0	0
Total liabilities measured at fair value	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,592	2,273
Other assets:
Life insurance policies	40,652	35,770
Total assets measured at fair value	42,244	38,043
Other current liabilities measured at fair value:
Contingent consideration	0
Other long-term liabilities measured at fair value:
Contingent consideration	0	0
Total liabilities measured at fair value	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Other assets:
Life insurance policies	0	0
Total assets measured at fair value	0	0
Other current liabilities measured at fair value:
Contingent consideration	23,531
Other long-term liabilities measured at fair value:
Contingent consideration	13,776	2,328
Total liabilities measured at fair value	$ 37,307	$ 2,328