Schedule of Share Based Awards Issued and Weighted Average Fair Value (Detail) (USD $)	6 Months Ended
Jul. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards Granted	217,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards Granted	100,000
Weighted Average Fair Value	$ 7.02
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards Granted	117,000
Weighted Average Fair Value	$ 20.64

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration