Fair Value Measurements, Valuation Techniques (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jul. 27, 2012	Jul. 29, 2011
Reconciliation of Retirement Benefit Plan Assets Measured at Fair Value Using Significant Unobservable Inputs
Beginning balance	$ 172	$ 191
Total realized losses and other-than-temporary impairment losses included in earnings		(1)
Total unrealized gains/(losses) included in other comprehensive income	2	2
Settlements	(1)	(2)
Ending balance	173	190
Corporate Debt Securities
Reconciliation of Retirement Benefit Plan Assets Measured at Fair Value Using Significant Unobservable Inputs
Beginning balance	10	17
Total realized losses and other-than-temporary impairment losses included in earnings		0
Total unrealized gains/(losses) included in other comprehensive income	0	0
Settlements	0	0
Ending balance	10	17
Auction Rate Securities
Reconciliation of Retirement Benefit Plan Assets Measured at Fair Value Using Significant Unobservable Inputs
Beginning balance	127	133
Total realized losses and other-than-temporary impairment losses included in earnings		0
Total unrealized gains/(losses) included in other comprehensive income	2	1
Settlements	0	0
Ending balance	129	134
Mortgage Backed Securities
Reconciliation of Retirement Benefit Plan Assets Measured at Fair Value Using Significant Unobservable Inputs
Beginning balance	29	35
Total realized losses and other-than-temporary impairment losses included in earnings		0
Total unrealized gains/(losses) included in other comprehensive income	0	0
Settlements	(1)	(2)
Ending balance	28	33
Other Asset-backed Securities
Reconciliation of Retirement Benefit Plan Assets Measured at Fair Value Using Significant Unobservable Inputs
Beginning balance	6	6
Total realized losses and other-than-temporary impairment losses included in earnings		(1)
Total unrealized gains/(losses) included in other comprehensive income	0	1
Settlements	0	0
Ending balance	$ 6	$ 6
Recurring | Level 3
Fair Value Inputs
Illiquidity Premium	6.00%
Recurring | Level 3 | Minimum
Fair Value Inputs
Years to Principal Recovery	2 years
Recurring | Level 3 | Maximum
Fair Value Inputs
Years to Principal Recovery	12 years
Recurring | Level 3 | Weighted Average
Fair Value Inputs
Years to Principal Recovery	3 years