Deferred Compensation And Retirement Plans (Weighted-Average Assumptions Used In Calculating The Benefit Obligations) (Detail)	Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2010	Apr. 30, 2009
Deferred Compensation Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate, beginning of year	3.79%	4.94%	5.61%	7.10%
Discount rate, end of year	3.79%	4.94%	5.61%	7.10%
Rate of compensation increase	0.00%	0.00%	0.00%
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate, beginning of year	3.79%	4.94%	5.61%	7.10%
Discount rate, end of year	3.79%	4.94%	5.61%	7.10%
Rate of compensation increase	0.00%	0.00%	0.00%

Expected rate of compensation increases (for pay-related plans).

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph j

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(2)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

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