Share-Based Payments (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Jul. 31, 2011
Share-Based Payments (Textuals) [Abstract]
Compensation cost related to nonvested share-based awards not yet recognized	$ 46,541
Weighted-average period of recognition	3.6

As of the latest balance-sheet date presented, the total compensation cost related to outstanding, nonvested share-based compensation awards not yet recognized (will be charged against earnings as services are performed or other vesting criteria are met).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph A240
-Subparagraph h

Name:	us-gaap_EmployeeServiceShareBasedCompensationUnrecognizedCompensationCostsOnNonvestedAwards
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant