Savings Plans (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Apr. 30, 2011	Apr. 30, 2010	Apr. 30, 2009
Savings Plans (Textual) [Abstract]
Maximum number of shares to be purchased under ESOP	1,134,120
Minimum number of years for allocation of shares in Esop	20
Interest on ESOP loan	one-half percentage point over prime
Interest expense incurred on ESOP debt	$ 127	$ 115	$ 261
Contribution to plan representing compensation expense			614
Special dividend on common share, in USD per share			$ 5.00
Dividends on unallocated shares	262	281	1,461
Principal Payments received from the ESOP	735	761	649
ESOP held unallocated shares	155,986
ESOP held allocated shares	856,318
Charges for defined contribution plan	$ 16,440	$ 15,625	$ 10,900

Dividends on unallocated shares.

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- Definition

The shares that, although not legally released, will be released by a future scheduled and committed debt service payment and will be allocated to employees for service rendered. The ESOP documents typically define the period of service to which the shares relate. ESOP shares are released to compensate employees directly.

+ Details

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- Definition

The rate at which ESOP loans bear interest.

+ Details

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- Definition

Maximum number of unallocated common shares ESOP may purchase of the Company's common shares at any one time.

+ Details

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- Definition

Minimum number of years for allocation of shares in Esop.

+ Details

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- Definition

Principal payments received from the ESOP.

+ Details

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- Definition

Savings Plans Textual.

+ Details

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- Definition

Special dividend on common share.

+ Details

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- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 11

+ Details

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- Definition

The amount of plan compensation cost recognized during the period.

+ References

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 93-6

-Paragraph 53

-Subparagraph c

+ Details

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- Definition

The shares in an ESOP trust that have been assigned to individual participant accounts based on a known formula. IRS rules require allocations to be nondiscriminatory generally based on compensation, length of service, or a combination of both. For any particular participant such shares may be vested, unvested, or partially vested.

+ References

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 93-6

-Paragraph 53

-Subparagraph d

+ Details

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- Definition

For grandfathered ESOP shares acquired prior to January 1, 1993, the actual interest incurred on debt for obligations that the employer may secure on behalf of the ESOP.

+ References

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 93-6

-Paragraph 53

-Subparagraph b

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

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 89-8

+ Details

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