Schedule of Derivatives Designated as Cash Flow Hedging Instruments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Nov. 30, 2014	Nov. 30, 2013	Nov. 30, 2014	Nov. 30, 2013
Derivative [Line Items]
Income (Loss) Recognized in OCI (Effective Portion)	$ (4,465)	$ (1,228)	$ (4,878)	$ 2,233
Income (Loss) Reclassified from Accumulated OCI (Effective Portion)	(1,493)	(1,869)	(3,437)	(3,248)
Interest Rate Contracts
Derivative [Line Items]
Income (Loss) Recognized in OCI (Effective Portion)		(181)		(384)
Interest Rate Contracts | Interest Expense
Derivative [Line Items]
Income (Loss) Reclassified from Accumulated OCI (Effective Portion)	(1,137)	(1,057)	(2,285)	(2,120)
Commodity Contracts
Derivative [Line Items]
Income (Loss) Recognized in OCI (Effective Portion)	(4,362)	(1,047)	(4,775)	2,617
Commodity Contracts | Cost Of Goods Sold
Derivative [Line Items]
Income (Loss) Reclassified from Accumulated OCI (Effective Portion)	(356)	(812)	(1,152)	(1,128)
Foreign Currency Contracts
Derivative [Line Items]
Income (Loss) Recognized in OCI (Effective Portion)	$ (103)		$ (103)