Schedule of Operations by Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Apr. 30, 2015	Apr. 30, 2014	Jan. 31, 2015
Segment Reporting Information [Line Items]
Total inventories	$ 397,998us-gaap_InventoryNet	$ 349,045us-gaap_InventoryNet	$ 358,237us-gaap_InventoryNet
Total property and equipment, net	899,324us-gaap_PropertyPlantAndEquipmentNet	836,244us-gaap_PropertyPlantAndEquipmentNet	889,232us-gaap_PropertyPlantAndEquipmentNet
Total net sales	739,010us-gaap_SalesRevenueNet	686,310us-gaap_SalesRevenueNet
General corporate expenses	(8,493)	(10,579)
Total income from operations	53,054us-gaap_OperatingIncomeLoss	59,821us-gaap_OperatingIncomeLoss
Operating Segments
Segment Reporting Information [Line Items]
Total income from operations	61,547	70,400
Operating Segments \| Retail Operations
Segment Reporting Information [Line Items]
Total inventories	359,112	320,961	314,940
Total property and equipment, net	895,399	831,854	885,200
Total net sales	685,009	640,430
Total income from operations	51,532	60,649
Operating Segments \| Wholesale Operations
Segment Reporting Information [Line Items]
Total inventories	38,886	28,084	43,297
Total property and equipment, net	3,925	4,390	4,032
Total net sales	57,614	48,290
Total income from operations	10,368	9,991
Intersegment Elimination
Segment Reporting Information [Line Items]
Total net sales	(3,613)	(2,410)
Total income from operations	$ (353)	$ (240)

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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