Schedule of Progression of Liabilities Created as Part of Transformation Plan, Combined with Reconciliation to Restructuring and Other Expense (Detail) (USD $)	12 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2010
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 7,629,000	$ 1,453,000
Expense	14,119,000	14,739,000
Payments	(18,212,000)	(8,401,000)
Adjustments	2,047,000	(162,000)
Ending Balance	5,583,000	7,629,000	1,453,000
Non-cash charges		203,000	3,408,000
Net gain on dispositions	(8,285,000)	(1,073,000)
Joint venture transaction	150,000	(11,216,000)
Restructuring and other expense	5,984,000	2,653,000	4,243,000
Early Retirement And Severance
Restructuring Cost and Reserve [Line Items]
Beginning Balance	7,220,000	893,000
Expense	245,000	8,687,000
Payments	(3,824,000)	(2,371,000)
Adjustments	1,251,000	11,000
Ending Balance	4,892,000	7,220,000
Facility Exit And Other Costs
Restructuring Cost and Reserve [Line Items]
Beginning Balance	409,000	560,000
Expense	9,116,000	6,052,000
Payments	(9,630,000)	(6,030,000)
Adjustments	796,000	(173,000)
Ending Balance	691,000	409,000
Professional Fees
Restructuring Cost and Reserve [Line Items]
Expense	4,758,000
Payments	$ (4,758,000)