Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Millions	Jan. 31, 2021	Jan. 26, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 11,348	$ 10,781
Unrealized Gain	3	0
Unrealized Loss	0	0
Estimated Fair Value	11,351	10,781
Cash Equivalents	637	10,780
Marketable Securities	10,714	1
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,442	592
Unrealized Gain	2	0
Unrealized Loss	0	0
Estimated Fair Value	4,444	592
Cash Equivalents	234	592
Marketable Securities	4,210	0
Debt securities issued by United States government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,975	1,096
Unrealized Gain	1	0
Unrealized Loss	0	0
Estimated Fair Value	2,976	1,096
Cash Equivalents	28	1,096
Marketable Securities	2,948	0
Debt securities issued by the United States Treasury
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,846	1,358
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	2,846	1,358
Cash Equivalents	25	1,358
Marketable Securities	2,821	0
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	705	27
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	705	27
Cash Equivalents	37	27
Marketable Securities	668	0
Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	313	7,507
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	313	7,507
Cash Equivalents	313	7,507
Marketable Securities	0	0
Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	67	200
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	67	200
Cash Equivalents		200
Marketable Securities	$ 67	0
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		1
Unrealized Gain		0
Unrealized Loss		0
Estimated Fair Value		1
Cash Equivalents		0
Marketable Securities		$ 1

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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