Marketable Securities - Summary of Securities (Details) - USD ($) $ in Millions	Apr. 28, 2019	Jan. 27, 2019
Summary of cash equivalents and marketable securities:
Amortized Cost	$ 7,692	$ 7,335
Unrealized Gain	3	1
Unrealized Loss	(4)	(12)
Estimated Fair Value	7,691	7,324
Reported as
Cash Equivalents	2,661	684
Marketable Securities	5,030	6,640
Corporate debt securities
Summary of cash equivalents and marketable securities:
Amortized Cost	2,899	2,626
Unrealized Gain	2	0
Unrealized Loss	(2)	(6)
Estimated Fair Value	2,899	2,620
Reported as
Cash Equivalents	1,048	25
Marketable Securities	1,851	2,595
Debt securities of United States government agencies
Summary of cash equivalents and marketable securities:
Amortized Cost	1,882	2,284
Unrealized Gain	0	0
Unrealized Loss	(1)	(4)
Estimated Fair Value	1,881	2,280
Reported as
Cash Equivalents	0	0
Marketable Securities	1,881	2,280
Debt securities issued by the United States Treasury
Summary of cash equivalents and marketable securities:
Amortized Cost	1,833	1,493
Unrealized Gain	0	0
Unrealized Loss	0	(1)
Estimated Fair Value	1,833	1,492
Reported as
Cash Equivalents	932	176
Marketable Securities	901	1,316
Money market funds
Summary of cash equivalents and marketable securities:
Amortized Cost	681	483
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	681	483
Reported as
Cash Equivalents	681	483
Marketable Securities	0	0
Foreign government bonds
Summary of cash equivalents and marketable securities:
Amortized Cost	183	209
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	183	209
Reported as
Cash Equivalents	0	0
Marketable Securities	183	209
Asset-backed securities
Summary of cash equivalents and marketable securities:
Amortized Cost	133	152
Unrealized Gain	0	0
Unrealized Loss	(1)	(1)
Estimated Fair Value	132	151
Reported as
Cash Equivalents	0	0
Marketable Securities	132	151
Mortgage-backed securities issued by United States government-sponsored enterprises
Summary of cash equivalents and marketable securities:
Amortized Cost	81	88
Unrealized Gain	1	1
Unrealized Loss	0	0
Estimated Fair Value	82	89
Reported as
Cash Equivalents	0	0
Marketable Securities	$ 82	$ 89