Retirement Plans (Details 4) (USD $) In Millions, unless otherwise specified	May 31, 2011	May 31, 2010
Cash And Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value	$ 409	$ 427
Actual %	3.00%	3.00%
Target %	1.00%	1.00%
Quoted Prices In Active Markets Level 1	107	145
Other Observable Inputs Level 2	302	282
Domestic Large Cap Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value	4,280	3,374
Actual %	27.00%	26.00%
Target %	24.00%	24.00%
Quoted Prices In Active Markets Level 1	26
Other Observable Inputs Level 2	4,254	3,374
Domestic Small To Mid Cap Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value	1,481	1,195
Actual %	10.00%	9.00%
Target %	9.00%	9.00%
Quoted Prices In Active Markets Level 1	1,481	1,195
International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value	2,013	1,502
Actual %	13.00%	12.00%
Target %	12.00%	12.00%
Quoted Prices In Active Markets Level 1	1,702	1,262
Other Observable Inputs Level 2	311	240
Private Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value	403	399
Actual %	3.00%	3.00%
Target %	5.00%	5.00%
Unobservable Inputs Level 3	403	399
Total Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target %	49.00%	49.00%
Corporate Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value	3,794	3,546
Actual %	24.00%	27.00%
Other Observable Inputs Level 2	3,794	3,546
United States Government Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value	3,135	2,537
Actual %	20.00%	19.00%
Other Observable Inputs Level 2	3,135	2,537
Mortgage Backed And Other Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value	66	122
Actual %		1.00%
Other Observable Inputs Level 2	66	122
Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value	(63)	(47)
Quoted Prices In Active Markets Level 1	(59)	(46)
Other Observable Inputs Level 2	(4)	(1)
Total Asset Class [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value	15,518	13,055
Actual %	100.00%	100.00%
Target %	100.00%	100.00%
Quoted Prices In Active Markets Level 1	3,257	2,556
Other Observable Inputs Level 2	11,858	10,100
Unobservable Inputs Level 3	$ 403	$ 399

- Definition

This item represents the amount of assets or liabilities, including financial instruments, which are measured at fair value on either a recurring or nonrecurring basis and fall within Level 2 of the fair value measurements hierarchy. Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include the following: (a) quoted prices for similar assets or liabilities in active markets; (b) quoted prices for identical or similar assets or liabilities in markets that are not active, that is, markets in which there are few transactions for the asset or liability, the prices are not current, or price quotations vary substantially either over time or among market makers (for example, some brokered markets), or in which little information is released publicly (for example, a principal-to-principal market); (c) inputs other than quoted prices that are observable for the asset or liability (for example, interest rates and yield curves observable at commonly quoted intervals, volatilities, prepayment speeds, loss severities, credit risks, and default rates); or (d) inputs that are derived principally from or corroborated by observable market data by correlation or other means (market-corroborated inputs).

+ Details