Related Parties (Details Textuals) (USD $) In Millions	12 Months Ended
	May 31, 2011	May 31, 2010	May 31, 2009
EMC Corporation [Member]
Related Party Transactions (Textuals) [Abstract]
Purchase from related parties	$ 5.7	$ 3.2	$ 4.5
Staples Inc [Member]
Related Party Transactions (Textuals) [Abstract]
Purchase from related parties	1.8	1.5	0.2
Dun & Bradstreet Corporation [Member]
Related Party Transactions (Textuals) [Abstract]
Purchase from related parties	$ 0.4	$ 0.4	$ 0.5