Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 23, 2015	Jan. 24, 2014	Jan. 23, 2015	Jan. 24, 2014
Other Comprehensive Income (Loss), Tax
Unrealized gain/(loss) on investments, tax expense/(benefit)	$ (20)	$ (34)	$ (7)	$ (71)
Net change in retirement obligations, tax expense/(benefit)	6	8	18	25
Unrealized gain/(loss) on derivatives, tax expense/(benefit)	$ 36	$ 27	$ 125	$ (25)