Long-Term Debt (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 25, 2011	Dec. 26, 2010	Dec. 27, 2009
Debt Instrument [Line Items]
Long-term debt, carrying cost	$ 1,400,872	$ 1,397,681
Long-term debt, fair value	1,524,266	1,455,466
Principal amounts included in carrying cost	1,384,895	1,384,895
Total principal amounts of long-term debt	1,384,895	1,384,895
Interest Rate Swap 6.125% Note Due 2014 [Member]
Derivative [Line Items]
Total notional amount of the interest rate swaps	400,000
(Gain) loss on interest rate swaps	(3,191)	(15,511)	2,725
Derivative asset, fair value	15,977	12,786
Maturity date	Dec. 31, 2014
Notes 6.35% Due 2040 [Member]
Debt Instrument [Line Items]
Long-term debt, carrying cost	500,000	500,000
Long-term debt, fair value	540,850	499,900
Interest rate on long-term debt (in hundredths)	6.35%	6.35%
Maturity date on long-term debt	Dec. 31, 2040	Dec. 31, 2040
Notes 6.125% Due 2014 [Member]
Debt Instrument [Line Items]
Long-term debt, carrying cost	440,977	437,786
Long-term debt, fair value	462,868	462,698
Interest rate on long-term debt (in hundredths)	6.125%	6.125%
Maturity date on long-term debt	Dec. 31, 2014	Dec. 31, 2014
Principal amounts included in carrying cost	425,000	425,000
Fair value adjustments included in carrying costs related to interest rate swaps	15,977	12,786
Total principal amounts of long-term debt	425,000	425,000
Range of interest rate adjustment dependent on the degree of decrease of the Company's credit rating, minimum (in hundredths)	0.25%	0.25%
Range of interest rate adjustment dependent on the degree of decrease of the Company's credit rating, maximum (in hundredths)	2.00%	2.00%
Notes 6.30% Due 2017 [Member]
Debt Instrument [Line Items]
Long-term debt, carrying cost	350,000	350,000
Long-term debt, fair value	400,400	382,830
Interest rate on long-term debt (in hundredths)	6.30%	6.30%
Maturity date on long-term debt	Dec. 31, 2017	Dec. 31, 2017
Range of interest rate adjustment dependent on the degree of decrease of the Company's credit rating, minimum (in hundredths)	0.25%	0.25%
Range of interest rate adjustment dependent on the degree of decrease of the Company's credit rating, maximum (in hundredths)	2.00%	2.00%
Debentures 6.60% Due 2028 [Member]
Debt Instrument [Line Items]
Long-term debt, carrying cost	109,895	109,895
Long-term debt, fair value	$ 120,148	$ 110,038
Interest rate on long-term debt (in hundredths)	6.60%	6.60%
Maturity date on long-term debt	Dec. 31, 2028	Dec. 31, 2028