Term Receivable and Trade Accounts Receivable Balances (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2012	Jan. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade and term receivables	$ 354,924	$ 347,075
Term receivables, long-term	220,355	167,425
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade and term receivables	133,494	153,733
Term receivables, short-term
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade and term receivables	$ 221,430	$ 193,342

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Subparagraph a(1)

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 4

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3-4)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_AccountsReceivableNetCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant