Restructuring Charges - Activities Related to Restructuring Reserves (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 27, 2017	Jan. 29, 2016	Jan. 27, 2017	Jan. 29, 2016
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period			$ 45
Net charges	$ 52	$ 0	52	$ 28
Cash payments			(72)
Balance at end of period	25		25
November 2016 Restructuring
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period			0
Net charges			52
Cash payments			(27)
Balance at end of period	25		25
March 2016 Restructuring
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period			45
Net charges			0
Cash payments			(45)
Balance at end of period	$ 0		$ 0
May 2015 Restructuring
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period				0
Net charges				28
Cash payments				(28)
Balance at end of period		$ 0		$ 0