INVESTMENTS IN SECURITIES (Details) - USD ($)	12 Months Ended
	Dec. 27, 2015	Dec. 28, 2014
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains recognized on available-for-sale securities	$ 1,200,000	$ 1,000,000
Gross realized losses recognized on available-for-sale securities	25,400	18,800
Cash equivalents, fixed income securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	290,795,000	204,286,000
Fair Value	290,795,000	204,286,000
Cash equivalents, other [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	54,831,000	80,000
Fair Value	$ 54,831,000	$ 80,000