Note 7. Employee Benefits (Detail) - Components of net periodic employee benefits expense: (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 25, 2012
Pension Plans, Defined Benefit [Member]
Interest cost	$ 4,700	$ 5,300
Expected return on plan assets	(5,750)	(5,925)
Amortization of net loss/(gain)	2,100	1,375
Net periodic benefit cost	1,050	750
Other Postretirement Benefit Plans, Defined Benefit [Member]
Service cost	50	50
Interest cost	225	450
Amortization of prior-service cost	25	325
Amortization of net loss/(gain)	(200)	(175)
Net periodic benefit cost	$ 100	$ 650