Marketable Securities - Summary of Securities (Details) - USD ($) $ in Millions	Oct. 27, 2019	Jan. 27, 2019
Summary of cash equivalents and marketable securities:
Amortized Cost	$ 9,657	$ 7,335
Unrealized Gain	0	1
Unrealized Loss	0	(12)
Estimated Fair Value	9,657	7,324
Reported as
Cash Equivalents	9,653	684
Marketable Securities	4	6,640
Debt securities issued by the United States Treasury
Summary of cash equivalents and marketable securities:
Amortized Cost	5,883	1,493
Unrealized Gain	0	0
Unrealized Loss	0	(1)
Estimated Fair Value	5,883	1,492
Reported as
Cash Equivalents	5,883	176
Marketable Securities	0	1,316
Corporate debt securities
Summary of cash equivalents and marketable securities:
Amortized Cost	1,293	2,626
Unrealized Gain	0	0
Unrealized Loss	0	(6)
Estimated Fair Value	1,293	2,620
Reported as
Cash Equivalents	1,293	25
Marketable Securities	0	2,595
Debt securities of United States government agencies
Summary of cash equivalents and marketable securities:
Amortized Cost	1,204	2,284
Unrealized Gain	0	0
Unrealized Loss	0	(4)
Estimated Fair Value	1,204	2,280
Reported as
Cash Equivalents	1,204	0
Marketable Securities	0	2,280
Money market funds
Summary of cash equivalents and marketable securities:
Amortized Cost	1,070	483
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	1,070	483
Reported as
Cash Equivalents	1,070	483
Marketable Securities	0	0
Foreign government debt securities
Summary of cash equivalents and marketable securities:
Amortized Cost	178	209
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	178	209
Reported as
Cash Equivalents	178	0
Marketable Securities	0	209
Certificates of deposit
Summary of cash equivalents and marketable securities:
Amortized Cost	25
Unrealized Gain	0
Unrealized Loss	0
Estimated Fair Value	25
Reported as
Cash Equivalents	25
Marketable Securities	0
Asset-backed securities
Summary of cash equivalents and marketable securities:
Amortized Cost	4	152
Unrealized Gain	0	0
Unrealized Loss	0	(1)
Estimated Fair Value	4	151
Reported as
Cash Equivalents	0	0
Marketable Securities	$ 4	151
Mortgage-backed securities issued by United States government-sponsored enterprises
Summary of cash equivalents and marketable securities:
Amortized Cost		88
Unrealized Gain		1
Unrealized Loss		0
Estimated Fair Value		89
Reported as
Cash Equivalents		0
Marketable Securities		$ 89