Fair Value Measurements, Fair Value Measured on Recurring Basis (Details) (Recurring, USD $) In Millions, unless otherwise specified	Oct. 26, 2012	Apr. 27, 2012
Assets:
Corporate debt securities	$ 3,697	$ 3,541
Auction rate securities	129	127
Mortgage-backed securities	1,060	839
U.S. government and agency securities	3,513	3,084
Foreign government and agency securities	47	67
Certificates of deposit	6	47
Other asset-backed securities	492	537
Marketable equity securities	260	253
Exchange-traded funds	45	46
Derivative assets	283	254
Total assets	9,532	8,795
Liabilities:
Derivative liabilities	131	82
Total liabilities	131	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	1,647	1,511
Foreign government and agency securities	0	0
Certificates of deposit	0	0
Other asset-backed securities	0	0
Marketable equity securities	260	253
Exchange-traded funds	45	46
Derivative assets	88	87
Total assets	2,040	1,897
Liabilities:
Derivative liabilities	45	37
Total liabilities	45	37
Level 2
Assets:
Corporate debt securities	3,687	3,531
Auction rate securities	0	0
Mortgage-backed securities	1,033	810
U.S. government and agency securities	1,866	1,573
Foreign government and agency securities	47	67
Certificates of deposit	6	47
Other asset-backed securities	487	531
Marketable equity securities	0	0
Exchange-traded funds	0	0
Derivative assets	195	167
Total assets	7,321	6,726
Liabilities:
Derivative liabilities	86	45
Total liabilities	86	45
Level 3
Assets:
Corporate debt securities	10	10
Auction rate securities	129	127
Mortgage-backed securities	27	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	5	6
Marketable equity securities	0	0
Exchange-traded funds	0	0
Derivative assets	0	0
Total assets	171	172
Liabilities:
Derivative liabilities	0	0
Total liabilities	$ 0	$ 0