COSTS AND ESTIMATED EARNINGS IN EXCESS OF BILLINGS, NET - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Jul. 31, 2012	Jul. 31, 2011
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net revenues	$ 16,685	$ 15,939
Contracts Accounted for under Percentage of Completion
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net revenues	$ 8,600	$ 8,300

Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration