Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies (Details Textual)

v3.3.1.900
Commitments and Contingencies (Details Textual) - USD ($)
6 Months Ended 12 Months Ended
Nov. 30, 2015
May. 31, 2015
Commitments and Contingencies (Textual)    
Commitments to purchase capital assets $ 6,500,000 $ 9,500,000
Line of Credit [Member]    
Line of Credit Facility [Line Items]    
Amount outstanding 0  
Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Amount outstanding $ 0  
Line of credit facility, initial term 5 years  
Maximum borrowing capacity $ 1,000,000,000 $ 750,000,000
Expiration date Aug. 05, 2020 Jun. 21, 2018
Standby Letters of Credit [Member]    
Line of Credit Facility [Line Items]    
Amount available $ 43,000,000 $ 43,000,000
Expiration date range of letters of credit April 2016 and December 2016  
Irrevocable stand by letters of credit amount outstanding $ 0