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Restructuring Charges - Activities Related to Restructuring Reserves (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 26, 2018	Oct. 27, 2017	Oct. 26, 2018	Oct. 27, 2017
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period			$ 6
Net charges	$ 0	$ 0	19	$ 0
Cash payments			(18)
Balance at end of period	7		7
May 2018 Restructuring
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period			0
Net charges			19
Cash payments			(17)
Balance at end of period	2		2
November 2016 Restructuring
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period			6	13
Net charges			0	0
Cash payments			(1)	(5)
Balance at end of period	$ 5	$ 8	$ 5	$ 8