Derivative Instruments And Hedging Activities (Schedule Of Summary Of Derivative Hedges) (Details) (USD $) In Thousands	3 Months Ended
	Aug. 31, 2011
Cash Flow Hedges [Member] | Derivatives Designated As Hedging Instruments [Member] | Interest Rate Contracts [Member]
Notional Amount	$ 100,000
Maturity Date	December 2014
Cash Flow Hedges [Member] | Derivatives Designated As Hedging Instruments [Member] | Commodity Contracts [Member]
Notional Amount	4,600
Maturity Date	December 2011
Derivatives Not Designated As Hedging Instruments [Member] | Maximum [Member] | Commodity Contracts [Member]
Maturity Date	October 2012
Derivatives Not Designated As Hedging Instruments [Member] | Minimum [Member] | Commodity Contracts [Member]
Maturity Date	November 2011
Derivatives Not Designated As Hedging Instruments [Member] | Foreign Currency Contracts [Member]
Notional Amount	52,070
Maturity Date	November 2011
Derivatives Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member]
Notional Amount	$ 9,250