Schedule Of Share-Based Compensation Activity Related To Exercise Of Stock Options (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Stock-Based Compensation [Abstract]
Cash received from exercises of stock options	$ 0	$ 0	$ 1
Stock exchanged at fair value upon exercises of stock options	1	0	14
Tax benefits realized from exercises of stock options	$ 0	$ 0	$ 4

Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (j)

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

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