Fair Value Measurements, Fair Value Measured on Recurring Basis (Details) (Recurring, USD $) In Millions, unless otherwise specified	Jul. 27, 2012	Apr. 27, 2012
Assets:
Corporate debt securities	$ 3,824	$ 3,541
Auction rate securities	129	127
Mortgage-backed securities	997	839
U.S. government and agency securities	3,570	3,084
Foreign government and agency securities	64	67
Certificates of deposit	35	47
Other asset-backed securities	472	537
Marketable equity securities	268	253
Exchange-traded funds	45	46
Derivative assets	408	254
Total assets	9,812	8,795
Liabilities:
Derivative liabilities	143	82
Total liabilities	143	82
Level 1
Assets:
Corporate debt securities	0	0
Auction rate securities	0	0
Mortgage-backed securities	0	0
U.S. government and agency securities	1,740	1,511
Foreign government and agency securities	0	0
Certificates of deposit	0	0
Other asset-backed securities	0	0
Marketable equity securities	268	253
Exchange-traded funds	45	46
Derivative assets	198	87
Total assets	2,251	1,897
Liabilities:
Derivative liabilities	49	37
Total liabilities	49	37
Level 2
Assets:
Corporate debt securities	3,814	3,531
Auction rate securities	0	0
Mortgage-backed securities	969	810
U.S. government and agency securities	1,830	1,573
Foreign government and agency securities	64	67
Certificates of deposit	35	47
Other asset-backed securities	466	531
Marketable equity securities	0	0
Exchange-traded funds	0	0
Derivative assets	210	167
Total assets	7,388	6,726
Liabilities:
Derivative liabilities	94	45
Total liabilities	94	45
Level 3
Assets:
Corporate debt securities	10	10
Auction rate securities	129	127
Mortgage-backed securities	28	29
U.S. government and agency securities	0	0
Foreign government and agency securities	0	0
Certificates of deposit	0	0
Other asset-backed securities	6	6
Marketable equity securities	0	0
Exchange-traded funds	0	0
Derivative assets	0	0
Total assets	173	172
Liabilities:
Derivative liabilities	0	0
Total liabilities	$ 0	$ 0