Selected Quarterly Financial Data - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Jan. 31, 2015	May. 03, 2014	Jan. 31, 2015
Income Statement [Abstract]
Litigation charge		$ 9.2	$ 9.5
Reversal of estimated expenses	$ 1.5

Amount charged against operating income increasing loss contingency liability, after adjustments to reduce previously estimated charges.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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