FAIR VALUE MEASUREMENT (Details) (USD $)	Sep. 26, 2014		Dec. 27, 2013
Fair Value Measurement [Line Items]
Marketable securities classified as available-for-sale	$ 1,746,000		$ 20,650,000
Restricted investments classified as held-to-maturity	93,751,000		86,940,000
Certificates of deposit (1)
Fair Value Measurement [Line Items]
Marketable securities classified as available-for-sale	1,746,000	[1]	9,900,000	[1]
Certificates of deposit (1) | Other assets
Fair Value Measurement [Line Items]
Marketable securities classified as available-for-sale securities due after one year			6,000,000
Carrying Value
Fair Value Measurement [Line Items]
Cash and cash equivalents	29,244,000	[2]	122,003,000	[2]
Marketable securities classified as available-for-sale	1,746,000	[3]	20,650,000	[3]
Carrying Value | Restricted Assets
Fair Value Measurement [Line Items]
Restricted cash and cash equivalents	50,313,000	[2]	57,085,000	[2]
Other restricted assets	9,269,000	[4]	10,795,000	[4]
Restricted investments classified as held-to-maturity	92,699,000		86,678,000
Total Fair Value
Fair Value Measurement [Line Items]
Cash and cash equivalents	29,244,000	[2]	122,003,000	[2]
Marketable securities classified as available-for-sale	1,746,000	[3]	20,650,000	[3]
Total Fair Value | Restricted Assets
Fair Value Measurement [Line Items]
Restricted cash and cash equivalents	50,313,000	[2]	57,085,000	[2]
Other restricted assets	9,269,000	[4]	10,795,000	[4]
Restricted investments classified as held-to-maturity	93,751,000		86,940,000
Level 1
Fair Value Measurement [Line Items]
Cash and cash equivalents	29,244,000	[2]	122,003,000	[2]
Marketable securities classified as available-for-sale	0	[3]	0	[3]
Level 1 | Restricted Assets
Fair Value Measurement [Line Items]
Restricted cash and cash equivalents	50,313,000	[2]	57,085,000	[2]
Other restricted assets	9,269,000	[4]	10,795,000	[4]
Restricted investments classified as held-to-maturity	0		0
Level 2
Fair Value Measurement [Line Items]
Cash and cash equivalents	0	[2]	0	[2]
Marketable securities classified as available-for-sale	1,746,000	[3]
Level 2 | Restricted Assets
Fair Value Measurement [Line Items]
Restricted cash and cash equivalents	0	[2]	0	[2]
Other restricted assets	0	[4]	0	[4]
Restricted investments classified as held-to-maturity			86,940,000
Level 3
Fair Value Measurement [Line Items]
Cash and cash equivalents	0	[2]	0	[2]
Marketable securities classified as available-for-sale	0	[3]		[3]
Level 3 | Restricted Assets
Fair Value Measurement [Line Items]
Restricted cash and cash equivalents	0	[2]	0	[2]
Other restricted assets	0	[4]	0	[4]
Restricted investments classified as held-to-maturity	$ 0		$ 0

[1] As of September 26, 2014, all our certificate of deposits were due within one year.

[2] Cash equivalents and restricted cash equivalents consist of money market funds, deposits, and investments with original maturities of three months or less.

[3] Marketable securities include CDs, VRDNs, and commercial paper, which are classified as available-for-sale. At September 26, 2014, all our marketable securities, which consist of CDs, had stated maturities of less than one year. At December 27, 2013, we had $6.0 million of CDs with maturities greater than one year, which are classified as Other assets on our Consolidated Balance Sheets. VRDNs with contractual maturities beyond one year are classified as short-term based on their highly liquid nature and because they represent the investment of cash that is available for current operations. Despite the long-term nature of their stated contractual maturities, we routinely buy and sell these securities and believe we have the ability to quickly sell them to the re-marketing agent at par value plus accrued interest in the event we decide to liquidate our investment in a particular VRDN.

[4] Other restricted assets primarily consists of deferred compensation plan accounts, which are comprised of mutual funds.