RESTRICTED CASH AND INVESTMENTS (Details) (USD $)	Sep. 26, 2014		Dec. 27, 2013
Restricted Cash and Investments [Line Items]
Cash collateral held by insurance carriers	$ 22,643,000		$ 23,747,000
Cash and cash equivalents held in Trust	25,806,000	[1]	31,474,000	[1]
Investments held in Trust	92,699,000		86,678,000
Cash collateral backing letters of credit	1,864,000		1,864,000
Other	9,269,000	[2]	10,795,000	[2]
Restricted cash and investments	152,281,000		154,558,000
Accrued interest on trust investments	900,000		800,000
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized Cost	92,699,000		86,678,000
Gross Unrealized Gain	1,321,000		1,043,000
Gross Unrealized Loss	(269,000)		(781,000)
Fair Value	93,751,000		86,940,000
Held-to-maturity Securities, Investment Maturities, Amortized Cost [Abstract]
Amortized Cost	92,699,000		86,678,000
Held-to-maturity Securities, Investment Maturities, Fair Value [Abstract]
Fair Value	93,751,000		86,940,000
Municipal debt securities
Restricted Cash and Investments [Line Items]
Investments held in Trust	54,267,000		54,133,000
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized Cost	54,267,000		54,133,000
Gross Unrealized Gain	988,000		722,000
Gross Unrealized Loss	(86,000)		(398,000)
Fair Value	55,169,000		54,457,000
Held-to-maturity Securities, Investment Maturities, Amortized Cost [Abstract]
Amortized Cost	54,267,000		54,133,000
Held-to-maturity Securities, Investment Maturities, Fair Value [Abstract]
Fair Value	55,169,000		54,457,000
Corporate debt securities
Restricted Cash and Investments [Line Items]
Investments held in Trust	27,785,000		19,694,000
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized Cost	27,785,000		19,694,000
Gross Unrealized Gain	194,000		180,000
Gross Unrealized Loss	(145,000)		(294,000)
Fair Value	27,834,000		19,580,000
Held-to-maturity Securities, Investment Maturities, Amortized Cost [Abstract]
Amortized Cost	27,785,000		19,694,000
Held-to-maturity Securities, Investment Maturities, Fair Value [Abstract]
Fair Value	27,834,000		19,580,000
Asset-backed securities
Restricted Cash and Investments [Line Items]
Investments held in Trust	10,647,000		12,851,000
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized Cost	10,647,000		12,851,000
Gross Unrealized Gain	139,000		141,000
Gross Unrealized Loss	(38,000)		(89,000)
Fair Value	10,748,000		12,903,000
Held-to-maturity Securities, Investment Maturities, Amortized Cost [Abstract]
Amortized Cost	10,647,000		12,851,000
Held-to-maturity Securities, Investment Maturities, Fair Value [Abstract]
Fair Value	10,748,000		12,903,000
Restricted Cash and Investments
Restricted Cash and Investments [Line Items]
Investments held in Trust	92,699,000
Held-to-maturity Securities, Reconciliation to Fair Value [Abstract]
Amortized Cost	92,699,000
Fair Value	93,751,000
Held-to-maturity Securities, Investment Maturities, Amortized Cost [Abstract]
Due in one year or less	10,797,000
Due after one year through five years	41,358,000
Due after five years through ten years	40,544,000
Amortized Cost	92,699,000
Held-to-maturity Securities, Investment Maturities, Fair Value [Abstract]
Due in one year or less	10,853,000
Due after one year through five years	41,874,000
Due after five years through ten years	41,024,000
Fair Value	$ 93,751,000

[1] Included in this amount is $0.9 million and $0.8 million of accrued interest at September 26, 2014 and December 27, 2013, respectively.

[2] consists of deferred compensation plan accounts, which are comprised of mutual funds.