Term Receivables and Trade Accounts Receivable - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Oct. 31, 2011	Oct. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net proceeds from sale of receivables	$ 28,295	$ 39,244

The cash inflow associated with the sale of receivables arising from the financing of goods and services.

No definition available.

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