Note 8. Employee Benefits (Details) - Components of net periodic employee benefits expense: (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 24, 2012	Jun. 30, 2013	Jun. 24, 2012
Pension Plan, Defined Benefit [Member]
Note 8. Employee Benefits (Details) - Components of net periodic employee benefits expense: [Line Items]
Interest cost	$ 4,772	$ 5,281	$ 9,472	$ 10,581
Expected return on plan assets	(5,725)	(5,927)	(11,475)	(11,852)
Amortization of net loss/(gain)	2,209	1,449	4,309	2,824
Net periodic benefit cost	1,256	803	2,306	1,553
Other Postretirement Benefit Plan, Defined Benefit [Member]
Note 8. Employee Benefits (Details) - Components of net periodic employee benefits expense: [Line Items]
Service cost	5	50	55	100
Interest cost	217	440	442	890
Amortization of prior-service cost	21	304	46	629
Amortization of net loss/(gain)	(222)	(235)	(422)	(410)
Net periodic benefit cost	$ 21	$ 559	$ 121	$ 1,209