Debt (Detail) - Schedule of debt (USD $) In Millions, unless otherwise specified	Nov. 30, 2011	May 31, 2011	Nov. 30, 2010
Debt, Long-term and Short-term, Combined Amount	$ 158.4	$ 203.4	$ 231.2
Debt, Long-term and Short-term, Combined Amount	159.5	207.5	233.6
Less lines of credit, short-term debt and current portion of long-term debt	(5.7)	(43.5)	(50.0)
Less lines of credit, short-term debt and current portion of long-term debt	(5.7)	(43.5)	(50.0)
Total long-term debt	152.7	159.9	181.2
Total long-term debt	153.8	164.0	183.6
Term Loan [Member]
Debt, Long-term and Short-term, Combined Amount		50.2	71.6
Debt, Long-term and Short-term, Combined Amount		50.2	71.6
Notes Due 2013 [Member]
Debt, Long-term and Short-term, Combined Amount	152.7	152.5	152.4
Debt, Long-term and Short-term, Combined Amount	153.8	156.6	154.8
Line of Credit [Member]
Debt, Long-term and Short-term, Combined Amount	5.7	0.7	7.2
Debt, Long-term and Short-term, Combined Amount	$ 5.7	$ 0.7	$ 7.2