Term Receivables and Trade Accounts Receivable - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Apr. 30, 2012	Apr. 30, 2011
Disclosure Term Receivables And Trade Accounts Receivable Additional Information [Abstract]
Billing Period (in days)	30 days
Net proceeds from sale of receivables	$ 7,457	$ 11,403

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