Term Receivable and Trade Accounts Receivable Balances (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2012	Jan. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade and term receivables	$ 354,919	$ 354,924
Term receivables, long-term	212,665	220,355
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade and term receivables	117,981	133,494
Term receivables, short-term
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade and term receivables	$ 236,938	$ 221,430

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