Employee Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 24, 2012	Jun. 26, 2011	Jun. 24, 2012	Jun. 26, 2011
Retirement expense for continuing operations
Service cost	$ 1,395	$ 1,369	$ 2,770	$ 2,769
Interest cost	23,049	22,688	45,949	46,238
Expected return on plan assets	(26,905)	(24,538)	(53,880)	(48,563)
Prior service cost amortization	7	7	7	7
Actuarial loss	3,268	1,425	6,343	2,825
Net pension expense	814	951	1,189	3,276
Net post-retirement benefit	(165)	(67)	(315)	(117)
Total retirement expenses-net	$ 649	$ 884	$ 874	$ 3,159