Debt (Detail) - Schedule of debt (USD $) In Millions	Aug. 31, 2011	May 31, 2011	Aug. 31, 2010
Debt, Long-term and Short-term, Combined Amount	$ 200.0	$ 203.4	$ 242.3
Debt, Long-term and Short-term, Combined Amount	200.4	207.5	239.2
Less lines of credit, short-term debt and current portion of long-term debt	(47.4)	(43.5)	(50.5)
Less lines of credit, short-term debt and current portion of long-term debt	(47.4)	(43.5)	(50.5)
Total long-term debt	152.6	159.9	191.8
Total long-term debt	153.0	164.0	188.7
Term Loan [Member]
Debt, Long-term and Short-term, Combined Amount	39.5	50.2	82.3
Debt, Long-term and Short-term, Combined Amount	39.5	50.2	82.3
Notes Due2013 [Member]
Debt, Long-term and Short-term, Combined Amount	152.6	152.5	152.3
Debt, Long-term and Short-term, Combined Amount	153.0	156.6	149.2
Line of Credit [Member]
Debt, Long-term and Short-term, Combined Amount	7.9	0.7	7.7
Debt, Long-term and Short-term, Combined Amount	$ 7.9	$ 0.7	$ 7.7