Summary of amounts recorded for TAS in balance sheet (Detail) (Thai Aviation Services, USD $) In Thousands, unless otherwise specified	Jul. 31, 2012	Apr. 30, 2012	Apr. 30, 2011
Receivables, net of allowances
Variable Interest Entity [Line Items]
Carrying amounts	$ 2,543	$ 2,408	$ 2,107
Maximum exposure to loss	2,543	2,408	2,107
Equity Method Investments
Variable Interest Entity [Line Items]
Carrying amounts	16,229	15,548	14,250
Maximum exposure to loss	$ 16,229	$ 15,548	$ 14,250

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph b

-URI http://asc.fasb.org/extlink&oid=7880789&loc=d3e5728-111685

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7880789&loc=d3e5747-111685

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4/FIN46(R)

-Paragraph C6

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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