Financial Instruments and Fair Value Measurements - Summary of Investments (Detail) - USD ($) $ in Millions	Jul. 28, 2017	Apr. 28, 2017
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	$ 2,718	$ 2,677
Gross unrealized gains	8	4
Gross unrealized losses	(3)	(4)
Estimated fair value	2,723	2,677
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	1,600	1,535
Gross unrealized gains	8	3
Gross unrealized losses	(1)	(2)
Estimated fair value	1,607	1,536
U.S. Treasury and Government Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	557	629
Gross unrealized gains	0	1
Gross unrealized losses	(2)	(2)
Estimated fair value	555	628
Foreign Government Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	21	21
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	21	21
Commercial Paper
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	409	362
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	409	362
Certificates of Deposit
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	99	99
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	99	99
Mutual Funds
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	32	31
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	$ 32	$ 31