Term Receivables and Trade Accounts Receivable - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Apr. 30, 2015	Apr. 30, 2014
Disclosure Term Receivables And Trade Accounts Receivable Additional Information [Abstract]
Billing period	30 days
Net proceeds from sale of receivables	$ 11,330	$ 10,043
Allowance for doubtful accounts adjustment
Statement
Valuation Allowances and Reserves, Charged to Cost and Expense		$ 1,691

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, charged to costs and expenses.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 09

-Article 12

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