Derivative Instruments And Hedging Activities (Schedule Of Derivatives Designated As Cash Flow Hedging Instruments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Feb. 29, 2012	Feb. 28, 2011	Feb. 29, 2012	Feb. 28, 2011
Derivative [Line Items]
Income (Loss) Recognized in Other Comprehensive Income (Effective Portion)	$ (112)	$ 3,362	$ (2,408)	$ (2,107)
Income (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)	(784)	(1,237)	(1,047)	(3,072)
Income (Loss) (Ineffective Portion) and Excluded from Effectiveness Testing
Interest Rate Contracts [Member]
Derivative [Line Items]
Income (Loss) Recognized in Other Comprehensive Income (Effective Portion)	(571)	1,227	(2,444)	(3,481)
Interest Rate Contracts [Member] | Interest Expense [Member]
Derivative [Line Items]
Income (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)	(1,042)	(1,022)	(3,040)	(2,986)
Income (Loss) (Ineffective Portion) and Excluded from Effectiveness Testing
Commodity Contracts [Member]
Derivative [Line Items]
Income (Loss) Recognized in Other Comprehensive Income (Effective Portion)	459	2,135	36	1,374
Commodity Contracts [Member] | Cost Of Goods Sold [Member]
Derivative [Line Items]
Income (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)	258	(215)	1,993	(86)
Income (Loss) (Ineffective Portion) and Excluded from Effectiveness Testing