Rental Income Under Sublease Agreements (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Operating Leased Assets [Line Items]
Rental income	$ 427	$ 1,691	$ 1,497

The amount of revenue recognized for the period under subleasing arrangements.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 55

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6584307&loc=d3e41620-112719

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

-Publisher FASB

-Name FASB Technical Bulletin (FTB)

-Number 88-1

-Paragraph 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Name:	us-gaap_OperatingLeasesIncomeStatementSubleaseRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration