Financial Instruments and Fair Value Measurements - Summary of Investments (Detail) - USD ($) $ in Millions	Apr. 27, 2018	Apr. 28, 2017
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	$ 2,738	$ 2,677
Gross unrealized gains	1	4
Gross unrealized losses	(44)	(4)
Estimated fair value	2,695	2,677
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	1,861	1,535
Gross unrealized gains	1	3
Gross unrealized losses	(39)	(2)
Estimated fair value	1,823	1,536
U.S. Treasury and Government Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	497	629
Gross unrealized gains	0	1
Gross unrealized losses	(5)	(2)
Estimated fair value	492	628
Foreign Government Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	4	21
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	4	21
Commercial Paper
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	230	362
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	230	362
Certificates of Deposit
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	115	99
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	115	99
Mutual Funds
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	31	31
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	$ 31	$ 31

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Section 50
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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