Fair Value Measurements (Unobservable Input Reconciliation) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 27, 2012	Jan. 28, 2011	Jan. 27, 2012	Jan. 28, 2011
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of	$ 174	$ 202	$ 191	$ 213
Total realized losses and other-than-temporary impairment losses included in earnings	(1)	0	(3)	(4)
Total unrealized gains/(losses) included in other comprehensive income	6	3	1	10
Settlements	(1)	(9)	(11)	(23)
Balance as of	178	196	178	196
Corporate Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of	10	17	17	16
Total realized losses and other-than-temporary impairment losses included in earnings	0	0	(1)	(2)
Total unrealized gains/(losses) included in other comprehensive income	0	0	1	4
Settlements	0	0	(7)	(1)
Balance as of	10	17	10	17
Auction Rate Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of	127	143	133	142
Total realized losses and other-than-temporary impairment losses included in earnings	0	0	0	0
Total unrealized gains/(losses) included in other comprehensive income	6	3	0	4
Settlements	0	(9)	0	(9)
Balance as of	133	137	133	137
Mortgage Backed Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of	31	36	35	39
Total realized losses and other-than-temporary impairment losses included in earnings	(1)	0	(1)	(2)
Total unrealized gains/(losses) included in other comprehensive income	0	0	(1)	2
Settlements	(1)	0	(4)	(3)
Balance as of	29	36	29	36
Other Asset-backed Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of	6	6	6	16
Total realized losses and other-than-temporary impairment losses included in earnings	0	0	(1)	0
Total unrealized gains/(losses) included in other comprehensive income	0	0	1	0
Settlements	0	0	0	(10)
Balance as of	$ 6	$ 6	$ 6	$ 6