Fair Value Measurements, Valuation Techniques (Details) (Recurring, Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 25, 2013	Oct. 26, 2012	Oct. 25, 2013	Oct. 26, 2012
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	$ 132	$ 173	$ 127	$ 172
Total realized losses and other-than-temporary impairment losses included in income	(2)		(2)
Total unrealized gains/(losses) included in other comprehensive income	1	(1)	6	1
Settlements	(13)	(1)	(13)	(2)
Ending balance	118	171	118	171
Corporate Debt Securities
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	10	10	10	10
Total realized losses and other-than-temporary impairment losses included in income	0		0
Total unrealized gains/(losses) included in other comprehensive income	0	0	0	0
Settlements	(1)	0	(1)	0
Ending balance	9	10	9	10
Auction Rate Securities
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	107	129	103	127
Total realized losses and other-than-temporary impairment losses included in income	(2)		(2)
Total unrealized gains/(losses) included in other comprehensive income	1	0	5	2
Settlements	(1)	0	(1)	0
Ending balance	105	129	105	129
Auction Rate Securities | Discounted Cash Flow
Fair Value Inputs
Illiquidity Premium			6.00%
Auction Rate Securities | Discounted Cash Flow | Minimum
Fair Value Inputs
Years to Principal Recovery			2 years
Auction Rate Securities | Discounted Cash Flow | Maximum
Fair Value Inputs
Years to Principal Recovery			12 years
Auction Rate Securities | Discounted Cash Flow | Weighted Average
Fair Value Inputs
Years to Principal Recovery			3 years
Mortgage Backed Securities
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	15	28	14	29
Total realized losses and other-than-temporary impairment losses included in income	0		0
Total unrealized gains/(losses) included in other comprehensive income	0	0	1	0
Settlements	(11)	(1)	(11)	(2)
Ending balance	4	27	4	27
Other Asset-backed Securities
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	0	6	0	6
Total realized losses and other-than-temporary impairment losses included in income	0		0
Total unrealized gains/(losses) included in other comprehensive income	0	(1)	0	(1)
Settlements	0	0	0	0
Ending balance	$ 0	$ 5	$ 0	$ 5