Components of Net Periodic Benefit (Income) Cost (Detail) - USD ($) $ in Thousands	4 Months Ended
	Apr. 22, 2017	Apr. 23, 2016
Pension plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 232	$ 255
Interest cost	4,008	4,532
Expected return on plan assets	(7,860)	(8,612)
Amortization of prior service cost (credit)	119	119
Amortization of net (gain) loss	1,958	1,798
Total net periodic benefit (income) cost	(1,543)	(1,908)
Post-retirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	79	123
Interest cost	70	95
Amortization of prior service cost (credit)	(65)	(65)
Amortization of net (gain) loss	(153)	(140)
Total net periodic benefit (income) cost	$ (69)	$ 13