Retirement Plans - Components of Net Periodic Pension and Other Postretirement Benefit Costs (Credits) (Detail) - USD ($)		12 Months Ended
	Sep. 30, 2015	Dec. 31, 2016	Jan. 02, 2016	Dec. 27, 2014
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Curtailment gain	$ 0
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Service cost		$ 3,849,000	$ 32,582,000	$ 27,729,000
Interest cost		40,459,000	39,628,000	37,468,000
Expected return on plan assets		(48,296,000)	(54,881,000)	(47,396,000)
Amortization of prior service cost (credit)		157,000	195,000	198,000
Amortization of net (gain) loss		8,255,000	10,394,000	2,294,000
Settlements		4,487,000	3,358,000	2,370,000
Special termination benefit			422,000
Net periodic benefit costs (credits)		8,911,000	31,698,000	22,663,000
Other Postretirement Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Service cost		37,000	37,000	79,000
Interest cost		296,000	264,000	318,000
Amortization of prior service cost (credit)		6,000	(62,000)	(334,000)
Amortization of net (gain) loss		(71,000)	14,000	(75,000)
Curtailment gain				(2,096,000)
Net periodic benefit costs (credits)		$ 268,000	$ 253,000	$ (2,108,000)