Investments, Marketable Securities, Credit Losses on and Maturities of Debt Securities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 26, 2012	Oct. 28, 2011	Oct. 26, 2012	Oct. 28, 2011	Apr. 27, 2012
Short-term
Available-for-sale securities, short-term	$ 916		$ 916		$ 1,344
Trading securities, short-term	0		0		0
Total short-term	916		916		1,344
Long-term
Available-for-sale securities, long-term	8,288		8,288		7,151
Trading securities, long-term	45		45		46
Total long-term	8,333		8,333		7,197
Credit Loss Portion of Other-than-temporary Impairments on Debt Securities
Beginning Balance	20	20	20	20
Credit losses recognized on securities previously not impaired	0	0	0	1
Reductions for securities sold during the period	0	0	0	(1)
Ending Balance	20	20	20	20
AFS Debt Maturities
Due in one year or less	1,330		1,330
Due after one year through five years	6,605		6,605
Due after five years through ten years	898		898
Due after ten years	111		111
Total debt securities	$ 8,944		$ 8,944