Financial Instruments and Fair Value Measurements - Summary of Investments (Detail) - USD ($) $ in Millions	Jul. 31, 2015	Apr. 24, 2015
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	$ 2,862	$ 3,681
Gross unrealized gains	4	11
Gross unrealized losses	(2)	0
Estimated fair value	2,864	3,692
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	1,712	2,249
Gross unrealized gains	3	9
Gross unrealized losses	(2)	0
Estimated fair value	1,713	2,258
U.S. Treasury and Government Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	838	1,056
Gross unrealized gains	1	2
Gross unrealized losses	0	0
Estimated fair value	839	1,058
Foreign Government Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	44	38
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	44	38
Commercial Paper
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	25	20
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	25	20
Certificates of Deposit
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	209	286
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	209	286
Mutual Funds
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	34	32
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	$ 34	$ 32