Consolidated Statements of Cash Flows (Parenthetical) (USD $) In Thousands	Apr. 30, 2011	Apr. 30, 2010	Apr. 30, 2009
Consolidated Statements of Cash Flows
Income tax refunds received	$ 4,762	$ 12,587	$ 158,862

The amount of the additional liability or refund received or expected based on a final settlement with a taxing authority.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319

Name:	us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant