Inventories - Summary of inventories (Details) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2013	Jan. 31, 2013	Jul. 31, 2012
Inventory Disclosure [Abstract]
Finished goods	$ 395,600	$ 271,155	$ 326,420
Raw materials and work-in-process	10,646	9,774	9,969
Inventories	$ 406,246	$ 280,929	$ 336,389

Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section BB

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 330

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SAB TOPIC 5.BB)

-URI http://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

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