Period over which consideration for sale of disposal group assets to be received.

No definition available.

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- Definition

Amount of gain (loss), after tax expense or benefit and not previously recognized, resulting from the sale of a business component.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e957-107759

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

+ Details

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Period Type:	duration

- Definition

Gain (loss) from sale or disposal of an organization or integrated set of activities (for example, but not limited to, a partnership or corporation) engaged in providing a product or service in a commercial, industrial, or professional environment.

+ References

No definition available.

+ Details

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- Details

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Balance Type:	na
Period Type:	duration

- Definition

The value of all consideration given or received by the Entity in the significant acquisition or disposal.

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

- Details

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Divestiture Transactions and Discontinued Operations - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	8 Months Ended	12 Months Ended		3 Months Ended
	Jul. 31, 2013	Dec. 31, 2013	Apr. 30, 2014	Apr. 30, 2012	Jul. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal of discontinued operations, net of tax	$ (378)	$ (378)	$ (378)	$ 725
BioFuels Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Undiscounted purchase consideration	2,000
Undiscounted purchase consideration paid in installments	5 years
Maine Energy Facility [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Undiscounted purchase consideration					6,650
Undiscounted purchase consideration paid in installments					21 years
Maine Energy Facility [Member] \| Maximum [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on divestiture					$ 1,000