Postretirement Medical Benefits - Summary of Net Periodic Benefit Cost Recognized (Detail) - Selling, General and Administrative Expenses [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Aug. 04, 2018	Jul. 29, 2017	Aug. 04, 2018	Jul. 29, 2017
Defined Benefit Plan Disclosure [Line Items]
Company service cost	$ 26	$ 40	$ 72	$ 91
Interest cost	38	38	75	74
Net prior service credit amortization	(174)	(174)	(347)	(347)
Amortization of unrecognized gain	(95)	3	(158)	(125)
Net periodic postretirement benefit cost	$ (205)	$ (93)	$ (358)	$ (307)