Pension and Other Postretirement Obligations - Components of Net Periodic Benefit Costs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 28, 2014	Sep. 29, 2013	Sep. 28, 2014	Sep. 29, 2013
Pension Obligations [Member]
Components of net periodic benefit cost:
Service cost	$ 1,762	$ 1,677	$ 5,853	$ 5,040
Interest cost	3,262	2,924	11,464	8,786
Expected return on plan assets	(4,154)	(3,396)	(14,405)	(10,193)
Amortization of prior service cost (credit)		(8)	1	(23)
Actuarial losses	1,718	1,662	5,164	4,995
Net periodic benefit cost	2,588	2,859	8,077	8,605
Other Postretirement Obligations [Member]
Components of net periodic benefit cost:
Service cost	(13)	33	48	101
Interest cost	(152)	517	924	1,600
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	18	(27)	(35)	(82)
Actuarial losses	72	278	425	876
Net periodic benefit cost	$ (75)	$ 801	$ 1,362	$ 2,495