Derivative Financial Instruments (Details) (USD $) In Millions	Jul. 31, 2011
Derivative Financial Instruments (Textuals) [Abstract]
Notional amount of foreign currencies to be purchased or sold	$ 10.0

Aggregate notional amount of foreign currency exchange rate derivatives. Notional amount refers to the number of currency units specified in the foreign currency derivative contract.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Notional Amount
-URI http://asc.fasb.org/extlink&oid=6519104

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