Fair Value Measurements, Valuation Techniques (Details) (Recurring, Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 24, 2014	Oct. 25, 2013	Oct. 24, 2014	Oct. 25, 2013
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs (level3)
Beginning balance	$ 108	$ 132	$ 106	$ 127
Total realized losses and other-than-temporary impairment losses included in income		(2)		(2)
Total unrealized gains/(losses) included in other comprehensive income	0	1	2	6
Settlements		(13)		(13)
Ending balance	108	118	108	118
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 (level3)
Beginning balance	9	10	9	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)		(1)
Ending balance	9	9	9	9
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 (level3)
Beginning balance	99	107	97	103
Total realized losses and other-than-temporary impairment losses included in income		(2)		(2)
Total unrealized gains/(losses) included in other comprehensive income	0	1	2	5
Settlements		(1)		(1)
Ending balance	99	105	99	105
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 (level3)
Beginning balance	0	15	0	14
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	1
Settlements		(11)		(11)
Ending balance	$ 0	$ 4	$ 0	$ 4