v2.3.0.11
Commitments And Contingencies (Details) (USD $)
3 Months Ended
Aug. 31, 2011
years
Aug. 31, 2010
Environmental remediation expense, period of remediation 5  
Estimated liability costs of remediation $ 916,000 $ 916,000
Estimated liability, measurement period 15  
Maximum [Member]
   
Environmental remediation expense 105,000  
Minimum [Member]
   
Environmental remediation expense $ 50,000