Pension Benefits - Net Periodic Pension Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended
	Dec. 27, 2009	Sep. 27, 2009	Jun. 28, 2009	Dec. 25, 2011	Dec. 26, 2010	Dec. 27, 2009
Pension Benefits
Service cost				$ 13,739	$ 13,941
Interest cost				113,284	116,125
Net pension curtailment gain				0	0	(53,965)
Qualified Plans [Member]
Pension Benefits
Service cost				12,079	12,045	28,266
Interest cost				99,991	102,523	102,757
Expected return on plan assets				111,813	113,625	113,359
Recognized actuarial loss				25,781	16,496	21,901
Amortization of prior service cost/(credit)				803	803	(4,728)
Net pension curtailment gain				0	0	(58,283)
Net periodic pension cost/(income)				26,841	18,242	(23,446)
Non-Qualified Plans [Member]
Pension Benefits
Service cost				1,660	1,896	1,687
Interest cost				13,293	13,602	14,431
Expected return on plan assets				0	0	0
Recognized actuarial loss				3,214	4,103	4,061
Amortization of prior service cost/(credit)				0	0	562
Net pension curtailment gain				0	0	4,318
Net periodic pension cost/(income)				18,167	19,601	25,059
Pension Plans, Defined Benefit [Member]
Pension Benefits
Service cost				13,739	13,941	29,953
Interest cost				113,284	116,125	117,188
Expected return on plan assets				111,813	113,625	113,359
Recognized actuarial loss				28,995	20,599	25,962
Amortization of prior service cost/(credit)				803	803	(4,166)
Net pension curtailment gain	56,671	2,510	196	0	0	(53,965)
Net periodic pension cost/(income)				$ 45,008	$ 37,843	$ 1,613