Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Aug. 31, 2013		Aug. 31, 2012
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ (3,820)
Translation adjustment	(79)		43
Ending balance	(3,857)		(4,847)
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	4,077		4,103
PROVISION FOR INCOME TAXES	277		268
Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	(67)	[1]	(100)	[1]
PROVISION FOR INCOME TAXES	25		37
Net income	(42)	[1]	(63)	[1]
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Amortization of actuarial losses [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	(95)	[1]	(129)	[1]
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Amortization of prior service credits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	28		29
Foreign currency translation gain (loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	102		61
Translation adjustment	(79)	[2]	43
Ending balance	23		104
Retirement plans adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(3,922)	[2]	(5,014)	[2]
Reclassification from AOCI	42		63
Ending balance	$ (3,880)		$ (4,951)

[1] Amounts in parentheses indicate debits to earnings.

[2] Amounts in parentheses indicate debits to AOCI.