Derivatives and Hedging Activities (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2011	Oct. 31, 2010
Gain (loss) on derivative instruments designated as cash flow hedges
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)	$ (11,508)	$ (6,720)
Cash Flow Hedging [Member]
Gain (loss) on derivative instruments designated as cash flow hedges
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)	230	(185)
Amount of Gain or (Loss) Reclassified From Accumulated OCI Into Income (Effective Portion)	(777)	(100)
Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion)	0	0
Cash Flow Hedging [Member] | Foreign Exchange Contract [Member]
Gain (loss) on derivative instruments designated as cash flow hedges
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)	230	(185)
Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | Cost of goods sold [Member]
Gain (loss) on derivative instruments designated as cash flow hedges
Amount of Gain or (Loss) Reclassified From Accumulated OCI Into Income (Effective Portion)	(777)	(100)
Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion)	$ 0	$ 0