Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 27, 2017	Jan. 29, 2016	Jan. 27, 2017	Jan. 29, 2016
Other Comprehensive Income (Loss), Tax
Unrealized (loss) gain on available-for-sale securities, tax (benefit) expense	$ (40)	$ (34)	$ (3)	$ (149)
Net change in retirement obligations, tax expense	5	10	15	30
Unrealized gain (loss) on derivatives, tax expense (benefit)	$ 55	$ (3)	$ 113	$ (36)