Derivative Financial Instruments (Details) (Not Designated as Hedging Instrument, USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Apr. 30, 2012
Fair value and presentation of derivatives
Asset Derivatives	$ 212	$ 612
Liability Derivatives	111	8
Foreign Exchange Contracts | Other Current Assets
Fair value and presentation of derivatives
Asset Derivatives	212	612
Foreign Exchange Contracts | Accrued Liabilities
Fair value and presentation of derivatives
Liability Derivatives	$ 111	$ 8