Supplemental Information (Textual) (Details) (Mexico [Member], USD $) In Millions, unless otherwise specified	Apr. 30, 2013	Apr. 30, 2012
Mexico [Member]
Segment Reporting Information [Line Items]
Net book value of property, plant, and equipment located in Mexico	$ 54	$ 55

Amount of long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets, located in foreign countries in total in which the entity holds assets.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 41

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 38

-Subparagraph b(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_EntityWideDisclosureOnGeographicAreasLongLivedAssetsInForeignCountries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant