Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Millions	Jan. 26, 2020	Jan. 27, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 10,781	$ 7,335
Unrealized Gain	0	1
Unrealized Loss	0	(12)
Estimated Fair Value	10,781	7,324
Cash Equivalents	10,780	684
Marketable Securities	1	6,640
Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,507	483
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	7,507	483
Cash Equivalents	7,507	483
Marketable Securities	0	0
Debt securities issued by the United States Treasury
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,358	1,493
Unrealized Gain	0	0
Unrealized Loss	0	(1)
Estimated Fair Value	1,358	1,492
Cash Equivalents	1,358	176
Marketable Securities	0	1,316
Debt securities issued by United States government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,096	2,284
Unrealized Gain	0	0
Unrealized Loss	0	(4)
Estimated Fair Value	1,096	2,280
Cash Equivalents	1,096	0
Marketable Securities	0	2,280
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	592	2,626
Unrealized Gain	0	0
Unrealized Loss	0	(6)
Estimated Fair Value	592	2,620
Cash Equivalents	592	25
Marketable Securities	0	2,595
Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	200	209
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	200	209
Cash Equivalents	200	0
Marketable Securities	0	209
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	27
Unrealized Gain	0
Unrealized Loss	0
Estimated Fair Value	27
Cash Equivalents	27
Marketable Securities	0
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1	152
Unrealized Gain	0	0
Unrealized Loss	0	(1)
Estimated Fair Value	1	151
Cash Equivalents	0	0
Marketable Securities	$ 1	151
Mortgage-backed securities issued by United States government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		88
Unrealized Gain		1
Unrealized Loss		0
Estimated Fair Value		89
Cash Equivalents		0
Marketable Securities		$ 89

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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