Summary of Fair Value and Carrying Value of Notes Payable (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2013	Jan. 31, 2013
Disclosure Summary Of Fair Value And Carrying Value Of Notes Payable [Abstract]
Fair value of notes payable	$ 310,955	$ 293,867
Notes payable	$ 221,353	$ 218,546

Carrying value as of the balance sheet date of all notes and loans payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

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

Name:	us-gaap_LongTermNotesAndLoans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant