Condensed Consolidated Statements of Comprehensive (Loss) Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 29, 2016	Jan. 23, 2015	Jan. 29, 2016	Jan. 23, 2015
Other Comprehensive Income (Loss), Tax
Unrealized (loss) gain on investments, tax (benefit) expense	$ (34)	$ (20)	$ (149)	$ (7)
Net change in retirement obligations, tax expense	10	6	30	18
Unrealized (loss) gain on derivatives, tax (benefit) expense	$ (3)	$ 36	$ (36)	$ 125