Employee Benefit Plans (Details) - Schedule of total weighted average asset allocations	May 31, 2013	May 31, 2012
Employee Benefit Plans (Details) - Schedule of total weighted average asset allocations [Line Items]
Pension Plans, Weighted Average Asset Allocations	100.00%	100.00%
Equity Securities [Member]
Employee Benefit Plans (Details) - Schedule of total weighted average asset allocations [Line Items]
Pension Plans, Weighted Average Asset Allocations	69.50%	63.50%
Debt Securities [Member]
Employee Benefit Plans (Details) - Schedule of total weighted average asset allocations [Line Items]
Pension Plans, Weighted Average Asset Allocations	24.00%	26.50%
Real Estate [Member]
Employee Benefit Plans (Details) - Schedule of total weighted average asset allocations [Line Items]
Pension Plans, Weighted Average Asset Allocations	1.00%	1.00%
Other Securities [Member]
Employee Benefit Plans (Details) - Schedule of total weighted average asset allocations [Line Items]
Pension Plans, Weighted Average Asset Allocations	5.50%	9.00%