Restructuring Charges - Restructuring Reserve (Details) - Cost Synergies Initiative [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 27, 2017	Jan. 29, 2016	Jan. 27, 2017	Jan. 29, 2016
Restructuring Reserve [Roll Forward]
Beginning balance			$ 250
Restructuring charges	$ 56	$ 55	214	$ 208
Payments/write-downs			(213)
Reversal of excess accrual	(35)	$ (19)	(42)	$ (32)
Ending balance	209		209
Employee Termination Costs [Member]
Restructuring Reserve [Roll Forward]
Beginning balance			213
Restructuring charges			152
Payments/write-downs			(146)
Reversal of excess accrual			(40)
Ending balance	179		179
Asset Write-downs [Member]
Restructuring Reserve [Roll Forward]
Beginning balance			0
Restructuring charges			18
Payments/write-downs			(18)
Reversal of excess accrual			0
Ending balance	0		0
Other Costs [Member]
Restructuring Reserve [Roll Forward]
Beginning balance			37
Restructuring charges			44
Payments/write-downs			(49)
Reversal of excess accrual			(2)
Ending balance	$ 30		$ 30