Components of Net Periodic Pension and Other Postretirement Benefit Costs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 29, 2013	Jun. 30, 2012	Jun. 29, 2013	Jun. 30, 2012
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 744	$ 927	$ 1,523	$ 1,870
Interest cost	11,905	16,186	23,847	32,344
Expected return on plan assets	(17,371)	(20,774)	(34,750)	(41,547)
Recognized actuarial loss	5,279	4,486	10,600	8,977
Net periodic benefit cost (income)	557	825	1,220	1,644
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	(6)	72	81	144
Interest cost	137	230	357	466
Recognized actuarial loss	31	45	131	101
Amortization of prior service credits	(987)	(1,001)	(1,975)	(2,004)
Net periodic benefit cost (income)	$ (825)	$ (654)	$ (1,406)	$ (1,293)