LONG-TERM DEBT (Details) - USD ($)	1 Months Ended	12 Months Ended
	Sep. 27, 2014	Dec. 26, 2015	Dec. 27, 2014	Oct. 17, 2014	Sep. 22, 2014
Long-term debt:
Aggregate principal amount		$ 250,200,000	$ 250,200,000
Total long-term debt		765,041,000	767,835,000
Less current installments of long-term debt		1,077,000	1,181,000
Long-term debt, excluding current installments		$ 763,964,000	$ 766,654,000
Repurchase amount through partial tender offer					$ 199,800,000
Effective interest rate (as a percent)		1.00%	1.00%
Minimum aggregate maturities of long-term debt
2016		$ 1,102,000
2017		893,000
2018		894,000
2019		752,000
2020		250,958,000
5.00% senior unsecured notes due 2044
Long-term debt:
Aggregate principal amount		250,000,000	$ 250,000,000		$ 250,000,000
Unamortized premium on senior unsecured notes		$ 1,138,000
Redemption price of notes, stated as a percentage of principal amount (as a percent)		100.00%
Interest rate on notes (as a percent)		5.00%			5.00%
5.25% senior unsecured notes due 2054
Long-term debt:
Aggregate principal amount		$ 250,000,000	250,000,000		$ 250,000,000
Unamortized premium on senior unsecured notes		$ 3,267,000
Redemption price of notes, stated as a percentage of principal amount (as a percent)		100.00%
Interest rate on notes (as a percent)		5.30%			5.00%
Unamortized discount on 5.00% and 5.25% senior unsecured notes
Long-term debt:
Unamortized premium on senior unsecured notes		$ (4,405,000)	(4,449,000)
6.625% senior unsecured notes due in April 2020
Long-term debt:
Aggregate principal amount		250,200,000			$ 250,200,000
Unamortized premium on senior unsecured notes		$ 4,518,000	5,429,000
Unamortized premium recognized as revenue	$ 4,439,000
Redemption price of notes, stated as a percentage of principal amount (as a percent)		100.00%
Cash prepayment expenses	$ 41,200,000
Interest rate on notes (as a percent)		6.60%			6.60%
Repurchase amount through partial tender offer					$ 199,800,000
Revolving credit agreement
Long-term debt:
Total long-term debt		$ 0	0
Previous borrowing capacity				$ 400,000,000
Maximum borrowing capacity				$ 600,000,000
Increase in borrowing capacity, maximum		200,000,000
Additional borrowing capacity		581,700,000
Standby letters of credit outstanding		$ 18,300,000
Revolving credit agreement | Minimum
Long-term debt:
Basis points added to variable rate (as a percent)		0.00%
Revolving credit agreement | Maximum
Long-term debt:
Basis points added to variable rate (as a percent)		6250.00%
Revolving credit agreement | LIBOR
Long-term debt:
Variable interest rate basis		LIBOR (based on a 1, 2, 3 or 6 month interest period, as selected by the Company)
Basis points added to variable rate (as a percent)		10000.00%
Variable interest rate, base period		1 month
Revolving credit agreement | LIBOR | Minimum
Long-term debt:
Basis points added to variable rate (as a percent)		10000.00%
Revolving credit agreement | LIBOR | Maximum
Long-term debt:
Basis points added to variable rate (as a percent)		16250.00%
Revolving credit agreement | Prime lending rate
Long-term debt:
Variable interest rate basis		prime lending rate
Revolving credit agreement | Federal Funds rate
Long-term debt:
Variable interest rate basis		Federal Funds rate
Basis points added to variable rate (as a percent)		5000.00%
IDR Bonds
Long-term debt:
Total long-term debt		$ 8,500,000	8,500,000
Other notes
Long-term debt:
Total long-term debt		6,228,000	$ 8,155,000
Short Term Bank Lines Of Credit
Long-term debt:
Additional borrowing capacity		103,300,000
Balance		$ 103,500,000