Cash Equivalents and Marketable Securities - Summary of Securities (Details) - USD ($) $ in Millions	Jul. 26, 2020	Jan. 26, 2020
Summary of cash equivalents and marketable securities:
Amortized Cost	$ 10,753	$ 10,781
Unrealized Gain	4	0
Unrealized Loss	0	0
Estimated Fair Value	10,757	10,781
Reported as
Cash Equivalents	3,050	10,780
Marketable Securities	7,707	1
Corporate debt securities
Summary of cash equivalents and marketable securities:
Amortized Cost	3,494	592
Unrealized Gain	3	0
Unrealized Loss	0	0
Estimated Fair Value	3,497	592
Reported as
Cash Equivalents	515	592
Marketable Securities	2,982	0
Debt securities issued by United States government agencies
Summary of cash equivalents and marketable securities:
Amortized Cost	2,101	1,096
Unrealized Gain	1	0
Unrealized Loss	0	0
Estimated Fair Value	2,102	1,096
Reported as
Cash Equivalents	50	1,096
Marketable Securities	2,052	0
Money market funds
Summary of cash equivalents and marketable securities:
Amortized Cost	2,053	7,507
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	2,053	7,507
Reported as
Cash Equivalents	2,053	7,507
Marketable Securities	0	0
Debt securities issued by the United States Treasury
Summary of cash equivalents and marketable securities:
Amortized Cost	1,956	1,358
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	1,956	1,358
Reported as
Cash Equivalents	0	1,358
Marketable Securities	1,956	0
Certificates of deposit
Summary of cash equivalents and marketable securities:
Amortized Cost	893	27
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	893	27
Reported as
Cash Equivalents	342	27
Marketable Securities	551	0
Foreign government bonds
Summary of cash equivalents and marketable securities:
Amortized Cost	256	200
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	256	200
Reported as
Cash Equivalents	90	200
Marketable Securities	$ 166	0
Asset-backed securities
Summary of cash equivalents and marketable securities:
Amortized Cost		1
Unrealized Gain		0
Unrealized Loss		0
Estimated Fair Value		1
Reported as
Cash Equivalents		0
Marketable Securities		$ 1