Benefit Plans (Details 6) (USD $) In Millions, unless otherwise specified	Feb. 25, 2012	Feb. 26, 2011	Feb. 27, 2010
Changes in Plan Assets
Total plan assets at fair value	$ 2,016	$ 1,896
Common Stock [Member]
Changes in Plan Assets
Total plan assets at fair value	606	751
Common collective trusts - fixed income [Member]
Changes in Plan Assets
Total plan assets at fair value	285	276
Common collective trusts - equity [Member]
Changes in Plan Assets
Total plan assets at fair value	332	199
Government Securities [Member]
Changes in Plan Assets
Total plan assets at fair value	210	161
Mutual Funds [Member]
Changes in Plan Assets
Total plan assets at fair value	198	149
Corporate bonds [Member]
Changes in Plan Assets
Total plan assets at fair value	113	143
Real Estate Partnerships [Member]
Changes in Plan Assets
Total plan assets at fair value	125	95
Private Equity [Member]
Changes in Plan Assets
Total plan assets at fair value	97	66
Mortgage backed securities [Member]
Changes in Plan Assets
Total plan assets at fair value	43	50
Other [Member]
Changes in Plan Assets
Total plan assets at fair value	7	6
Level 1 [Member]
Changes in Plan Assets
Total plan assets at fair value	725	802
Level 1 [Member] | Common Stock [Member]
Changes in Plan Assets
Total plan assets at fair value	606	718
Level 1 [Member] | Government Securities [Member]
Changes in Plan Assets
Total plan assets at fair value	119	68
Level 1 [Member] | Corporate bonds [Member]
Changes in Plan Assets
Total plan assets at fair value		15
Level 1 [Member] | Other [Member]
Changes in Plan Assets
Total plan assets at fair value		1
Level 2 [Member]
Changes in Plan Assets
Total plan assets at fair value	1,069	933
Level 2 [Member] | Common Stock [Member]
Changes in Plan Assets
Total plan assets at fair value		33
Level 2 [Member] | Common collective trusts - fixed income [Member]
Changes in Plan Assets
Total plan assets at fair value	285	276
Level 2 [Member] | Common collective trusts - equity [Member]
Changes in Plan Assets
Total plan assets at fair value	332	199
Level 2 [Member] | Government Securities [Member]
Changes in Plan Assets
Total plan assets at fair value	91	93
Level 2 [Member] | Mutual Funds [Member]
Changes in Plan Assets
Total plan assets at fair value	198	149
Level 2 [Member] | Corporate bonds [Member]
Changes in Plan Assets
Total plan assets at fair value	113	128
Level 2 [Member] | Mortgage backed securities [Member]
Changes in Plan Assets
Total plan assets at fair value	43	50
Level 2 [Member] | Other [Member]
Changes in Plan Assets
Total plan assets at fair value	7	5
Level 3 [Member]
Changes in Plan Assets
Total plan assets at fair value	222	161
Level 3 [Member] | Real Estate Partnerships [Member]
Changes in Plan Assets
Total plan assets at fair value	125	95
Level 3 [Member] | Private Equity [Member]
Changes in Plan Assets
Total plan assets at fair value	$ 97	$ 66	$ 35