Fair Value Measurements, Fair Value Measured on Recurring Basis (Details) (Recurring, USD $) In Millions, unless otherwise specified	Jan. 25, 2013	Apr. 27, 2012
Level 1
Assets:
Corporate debt securities	$ 0	$ 0
Auction rate securities	0	0
Mortgage-backed securities	0	0
U.S. government and agency securities	1,953	1,511
Foreign government and agency securities	0	0
Certificates of deposit	0	0
Other asset-backed securities	0	0
Marketable equity securities	233	253
Exchange-traded funds	49	46
Derivative assets	116	87
Total assets	2,351	1,897
Liabilities:
Derivative liabilities	88	37
Total liabilities	88	37
Level 2
Assets:
Corporate debt securities	4,214	3,531
Auction rate securities	0	0
Mortgage-backed securities	1,024	810
U.S. government and agency securities	1,810	1,573
Foreign government and agency securities	34	67
Certificates of deposit	6	47
Other asset-backed securities	502	531
Marketable equity securities	0	0
Exchange-traded funds	0	0
Derivative assets	168	167
Total assets	7,758	6,726
Liabilities:
Derivative liabilities	74	45
Total liabilities	74	45
Level 3
Assets:
Corporate debt securities	10	10
Auction rate securities	134	127
Mortgage-backed securities	26	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	176	172
Liabilities:
Derivative liabilities	0	0
Total liabilities	0	0
Estimate of Fair Value, Fair Value Disclosure [Member]
Assets:
Corporate debt securities	4,224	3,541
Auction rate securities	134	127
Mortgage-backed securities	1,050	839
U.S. government and agency securities	3,763	3,084
Foreign government and agency securities	34	67
Certificates of deposit	6	47
Other asset-backed securities	508	537
Marketable equity securities	233	253
Exchange-traded funds	49	46
Derivative assets	284	254
Total assets	10,285	8,795
Liabilities:
Derivative liabilities	162	82
Total liabilities	$ 162	$ 82