Marketable Securities - Summary of Securities (Details) - USD ($) $ in Millions	Jul. 28, 2019	Jan. 27, 2019
Summary of cash equivalents and marketable securities:
Amortized Cost	$ 8,371	$ 7,335
Unrealized Gain	1	1
Unrealized Loss	0	(12)
Estimated Fair Value	8,372	7,324
Reported as
Cash Equivalents	7,002	684
Marketable Securities	1,370	6,640
Money market funds
Summary of cash equivalents and marketable securities:
Amortized Cost	2,868	483
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	2,868	483
Reported as
Cash Equivalents	2,868	483
Marketable Securities	0	0
Debt securities issued by the United States Treasury
Summary of cash equivalents and marketable securities:
Amortized Cost	2,161	1,493
Unrealized Gain	0	0
Unrealized Loss	0	(1)
Estimated Fair Value	2,161	1,492
Reported as
Cash Equivalents	1,833	176
Marketable Securities	328	1,316
Corporate debt securities
Summary of cash equivalents and marketable securities:
Amortized Cost	2,103	2,626
Unrealized Gain	1	0
Unrealized Loss	0	(6)
Estimated Fair Value	2,104	2,620
Reported as
Cash Equivalents	1,282	25
Marketable Securities	822	2,595
Debt securities of United States government agencies
Summary of cash equivalents and marketable securities:
Amortized Cost	1,120	2,284
Unrealized Gain	0	0
Unrealized Loss	0	(4)
Estimated Fair Value	1,120	2,280
Reported as
Cash Equivalents	995	0
Marketable Securities	125	2,280
Foreign government debt securities
Summary of cash equivalents and marketable securities:
Amortized Cost	45	209
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	45	209
Reported as
Cash Equivalents	0	0
Marketable Securities	45	209
Asset-backed securities
Summary of cash equivalents and marketable securities:
Amortized Cost	44	152
Unrealized Gain	0	0
Unrealized Loss	0	(1)
Estimated Fair Value	44	151
Reported as
Cash Equivalents	0	0
Marketable Securities	44	151
Certificates of deposit
Summary of cash equivalents and marketable securities:
Unrealized Gain	0
Unrealized Loss	0
Estimated Fair Value	24
Reported as
Cash Equivalents	24
Marketable Securities	0
Mortgage-backed securities issued by United States government-sponsored enterprises
Summary of cash equivalents and marketable securities:
Amortized Cost	6	88
Unrealized Gain	0	1
Unrealized Loss	0	0
Estimated Fair Value	6	89
Reported as
Cash Equivalents	0	0
Marketable Securities	$ 6	$ 89