Fair Value Measurements, Valuation Techniques (Details) (Recurring, Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 24, 2014	Jan. 25, 2013	Jan. 24, 2014	Jan. 25, 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	$ 118	$ 171	$ 127	$ 172
Total realized losses and other-than-temporary impairment losses included in income	(3)		(5)
Total unrealized gains/(losses) included in other comprehensive income	(3)	5	3	6
Settlements	(7)		(20)	(2)
Ending balance	105	176	105	176
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	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	(1)	0	(1)
Settlements	0		(1)	0
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
Beginning balance	105	129	103	127
Total realized losses and other-than-temporary impairment losses included in income	(3)		(5)
Total unrealized gains/(losses) included in other comprehensive income	(3)	5	2	7
Settlements	(3)		(4)	0
Ending balance	96	134	96	134
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	4	27	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	(4)		(15)	(2)
Ending balance	0	27	0	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	5	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	0
Settlements	0		0	0
Ending balance	$ 0	$ 6	$ 0	$ 6