Note 8. Employee Benefits (Detail) - Net Periodic Employee Benefits (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 24, 2012	Jun. 26, 2011	Jun. 24, 2012	Jun. 26, 2011
Pension Plans, Defined Benefit [Member]
Interest cost	$ 5,281	$ 5,613	$ 10,581	$ 11,213
Expected return on plan assets	(5,927)	(5,823)	(11,852)	(11,998)
Amortization of net loss/(gain)	1,449	947	2,824	1,897
Net periodic benefit cost	803	737	1,553	1,112
Other Postretirement Benefit Plans, Defined Benefit [Member]
Service cost	50	63	100	113
Interest cost	440	405	890	955
Amortization of prior-service cost	304	411	629	861
Amortization of net loss/(gain)	(235)	(388)	(410)	(513)
Net periodic benefit cost	$ 559	$ 491	$ 1,209	$ 1,416