Income Tax - Carryforwards (Details) (USD $) In Millions, unless otherwise specified	May 31, 2012
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 14.2
Foreign Country [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	25.5
Domestic Country [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	2.9
Capital loss carryforwards	$ 56.2