EMPLOYEE BENEFIT PLANS (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	May 31, 2012	May 31, 2012	May 31, 2011	May 31, 2010
Defined Benefit Pension Plan Liabilities, Current			$ 1.3
Defined Benefit Post Retirement Plan Unrecognized Prior Service Credit	0.8	0.8
Percentage Of Federal Subsidy To Sponsors Of Retiree Health Care Benefit Plans		28.00%
Prescription Drug Benefit, Reduction in Accumulated Postretirement Benefit Obligation for Subsidy	2.9	2.9	3.0	2.8
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	7.70%
Other Comprehensive Income Defined Benefit Plans Tax Benefit		6.5
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax		(6.5)	4.0	(9.1)
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	10.6	10.6
Defined Retirement Plan Contributed		7.4	6.9	5.0
Pension Plans, Defined Benefit [Member] | Estimated Net Loss [Member]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year		2.2
Pension Plans, Defined Benefit [Member]
Defined Benefit Pension Plan Settlements Liabilities			1.2
Defined Benefit Plan Settlements Expense			4.2
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets		7.70%	7.50%	7.70%
Other Postretirement Benefit Plans, Defined Benefit [Member] | Estimated Net Loss [Member]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year		3.8
Other Postretirement Benefit Plans, Defined Benefit [Member] | Prior Service Cost [Member]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year		$ 0.4