Fair Value Measurements, Valuation Techniques (Details) (Recurring, Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended
	Jul. 25, 2014	Jul. 26, 2013
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	$ 106	$ 127
Total unrealized gains/(losses) included in other comprehensive income	2	5
Ending balance	108	132
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	9	10
Total unrealized gains/(losses) included in other comprehensive income	0	0
Ending balance	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	97	103
Total unrealized gains/(losses) included in other comprehensive income	2	4
Ending balance	99	107
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	0	14
Total unrealized gains/(losses) included in other comprehensive income	0	1
Ending balance	$ 0	$ 15