Long-Term Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 27, 2015	Dec. 28, 2014
Debt Instrument [Line Items]
Long-term debt	$ 1,547,115	$ 1,545,853
Carrying Cost	1,559,895	1,559,895
Deferred Debt Expenses	12,780	14,042
Fair Value	1,638,384	1,753,738
Aggregate Amount of Long-Term Debt Maturing in Next 5 Years	350,000
Fair value at date of interest rate swap contract settlement	33,306
Notes 6.35% Due 2040 [Member]
Debt Instrument [Line Items]
Carrying Cost	500,000	500,000
Fair Value	$ 556,300	$ 617,700
Interest rate on long-term debt	6.35%
Long-term debt, principal amount	$ 500,000	$ 500,000
Maturity Date	2040
Notes 6.30% Due 2017 [Member]
Debt Instrument [Line Items]
Carrying Cost	$ 350,000	$ 350,000
Fair Value	$ 374,045	$ 387,660
Interest rate on long-term debt	6.30%
Long-term debt, principal amount	$ 350,000	$ 350,000
Maturity Date	2017
Range of interest rate adjustment dependent on the degree of decrease of the Company's credit rating, minimum	0.25%	0.25%
Range of interest rate adjustment dependent on the degree of decrease of the Company's credit rating, maximum	2.00%	2.00%
Debentures 6.60% Due 2028 [Member]
Debt Instrument [Line Items]
Carrying Cost	$ 109,895	$ 109,895
Fair Value	$ 121,269	$ 128,698
Interest rate on long-term debt	6.60%
Long-term debt, principal amount	$ 109,895	$ 109,895
Maturity Date	2028
Notes 3.15% Due 2021 Member [Member]
Debt Instrument [Line Items]
Carrying Cost	$ 300,000	$ 300,000
Fair Value	$ 300,060	$ 302,700
Interest rate on long-term debt	3.15%
Long-term debt, principal amount	$ 300,000	$ 300,000
Maturity Date	2021
Fair value at date of interest rate swap contract settlement	$ 6,373
Notes 5.10% Due 2044 [Member]
Debt Instrument [Line Items]
Carrying Cost	300,000	$ 300,000
Fair Value	$ 286,710	$ 316,980
Interest rate on long-term debt	5.10%
Long-term debt, principal amount	$ 300,000	$ 300,000
Maturity Date	2044
Fair value at date of interest rate swap contract settlement	$ 26,933