Purchased Technology and Other Intangible Asset Amortization Expenses (Detail) (Purchased Technology And Other Intangible Asset, USD $) In Thousands, unless otherwise specified	12 Months Ended
Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Purchased Technology And Other Intangible Asset
Goodwill and Intangible Assets Disclosure [Line Items]
Purchased technology and other intangible asset amortization expenses	$ 15,701	$ 21,118	$ 23,196

Aggregate amount of intangible asset amortization recognized as expense during the period.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph a(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16323-109275

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration