RESTRICTED CASH AND INVESTMENTS (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 28, 2021	Mar. 29, 2020	Dec. 27, 2020
Restricted Cash and Investments [Line Items]
Cash collateral held by insurance carriers	$ 26,745		$ 26,025
Cash and cash equivalents held in Trust	25,586		29,410
Investments held in Trust	145,244		152,247
Deferred compensation investments	5,821		5,915
Company owned life insurance policies	26,950		26,267
Other restricted cash and cash equivalents	832		670
Restricted cash and investments	231,178		240,534
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized cost of held-to-maturity investments	145,244		152,247
Gross unrealized gains	4,968		6,090
Gross unrealized losses	(276)		(41)
Fair value	149,936		158,296
Held-to-maturity securities, amortized cost [Abstract]
Amortized cost of held-to-maturity investments	145,244		152,247
Held-to-maturity securities, fair value [Abstract]
Fair value	149,936		158,296
Unrealized gains (losses) on Investments	(877)	$ (4,841)
Municipal debt securities
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized cost of held-to-maturity investments	65,840		67,287
Gross unrealized gains	2,880		3,436
Gross unrealized losses	0		0
Fair value	68,720		70,723
Held-to-maturity securities, amortized cost [Abstract]
Amortized cost of held-to-maturity investments	65,840		67,287
Held-to-maturity securities, fair value [Abstract]
Fair value	68,720		70,723
Corporate debt securities
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized cost of held-to-maturity investments	78,056		83,467
Gross unrealized gains	1,974		2,511
Gross unrealized losses	(276)		(41)
Fair value	79,754		85,937
Held-to-maturity securities, amortized cost [Abstract]
Amortized cost of held-to-maturity investments	78,056		83,467
Held-to-maturity securities, fair value [Abstract]
Fair value	79,754		85,937
Agency mortgage-backed securities
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized cost of held-to-maturity investments	351		493
Gross unrealized gains	14		19
Gross unrealized losses	0		0
Fair value	365		512
Held-to-maturity securities, amortized cost [Abstract]
Amortized cost of held-to-maturity investments	351		493
Held-to-maturity securities, fair value [Abstract]
Fair value	365		512
U.S. government and agency securities
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized cost of held-to-maturity investments	997		1,000
Gross unrealized gains	100		124
Gross unrealized losses	0		0
Fair value	1,097		1,124
Held-to-maturity securities, amortized cost [Abstract]
Amortized cost of held-to-maturity investments	997		1,000
Held-to-maturity securities, fair value [Abstract]
Fair value	1,097		$ 1,124
Restricted cash and investments
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized cost of held-to-maturity investments	145,244
Fair value	149,936
Held-to-maturity securities, amortized cost [Abstract]
Due in one year or less	22,519
Due after one year through five years	109,541
Due after five years through ten years	13,184
Amortized cost of held-to-maturity investments	145,244
Held-to-maturity securities, fair value [Abstract]
Due in one year or less	22,675
Due after one year through five years	113,285
Due after five years through ten years	13,976
Fair value	$ 149,936

Held-to-maturity Securities, Adjustments for Fair Value Calculation [Abstract]

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Carrying amount of cash and investment securities on deposit with state regulatory authorities in connection with capital requirements.

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