XML 98 R64.htm IDEA: XBRL DOCUMENT v2.4.0.6
Postretirement Benefit Costs for Health Care and Life Insurance (Detail) (Other Postretirement Benefit Plans, Defined Benefit, USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 25, 2011
Dec. 26, 2010
Dec. 27, 2009
Other Postretirement Benefit Plans, Defined Benefit
     
Defined Benefit Plan Disclosure [Line Items]      
Service cost-benefits earned during the period $ 611 $ 713 $ 1,405
Interest cost on net benefit obligation 9,205 10,606 13,339
Amortization of prior service credit (19,510) (19,377) (15,689)
Amortization of actuarial loss 5,444 4,949 4,695
Net periodic (benefit) cost $ (4,250) $ (3,109) $ 3,750