Components of Net Periodic Benefit (Income) Cost (Detail) - USD ($) $ in Thousands	4 Months Ended
	Apr. 21, 2018	Apr. 22, 2017
Defined Benefit Plan Disclosure [Line Items]
Settlement loss	$ 4,668
Pension plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	288	$ 232
Interest cost	3,124	4,008
Expected return on plan assets	(5,407)	(7,860)
Settlement loss	4,668
Amortization of prior service cost (credit)	100	119
Amortization of net (gain) loss	1,573	1,958
Total net periodic pension cost (income)	4,346	(1,543)
Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	89	79
Interest cost	72	70
Amortization of prior service cost (credit)	(65)	(65)
Amortization of net (gain) loss	(133)	(153)
Total net periodic pension cost (income)	$ (37)	$ (69)