Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 25, 2013	Jan. 27, 2012	Jan. 25, 2013	Jan. 27, 2012
Other Comprehensive Income (Loss), Tax
Unrealized gain/(loss) on investments, tax expense/(benefit)	$ (19)	$ (89)	$ (15)	$ (61)
Net change in retirement obligations, tax expense/(benefit)	7	6	26	18
Unrealized gain/(loss) on derivatives, tax expense/(benefit)	$ (2)	$ 59	$ (18)	$ 106