Quarterly report pursuant to Section 13 or 15(d)

Goodwill and Intangible Assets, Net of Accumulated Amortization (Details Textual)

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Goodwill and Intangible Assets, Net of Accumulated Amortization (Details Textual) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Nov. 30, 2013
Nov. 30, 2012
Nov. 30, 2013
Nov. 30, 2012
May 31, 2013
Goodwill and Intangible Assets, Net of Accumulated Amortization (Textual)          
Goodwill $ 540.0   $ 540.0   $ 533.9
Amortization expense relating to intangible assets $ 3.8 $ 4.7 $ 7.5 $ 9.4