Components of Net Periodic Benefit Cost/(Credit) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Oct. 02, 2011	Sep. 30, 2012	Oct. 02, 2011
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 96	$ 141	$ 321	$ 416
Interest cost	15,355	16,891	46,090	50,670
Expected return on plan assets	(17,024)	(17,000)	(51,077)	(50,998)
Amortization of net actuarial loss, prior service cost and transition asset	3,592	1,695	10,754	5,080
Total benefit cost/(credit)	2,019	1,727	6,088	5,168
Post-retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	22	19	67	57
Interest cost	657	702	1,950	1,948
Expected return on plan assets	(953)	(1,032)	(2,859)	(3,097)
Amortization of net actuarial loss, prior service cost and transition asset	523	237	1,513	414
Total benefit cost/(credit)	$ 249	$ (74)	$ 671	$ (678)