Marketable Securities (Details) - USD ($) $ in Millions	Jan. 28, 2018	Jan. 29, 2017
Classified as:
Amortized cost	$ 6,916	$ 5,484
Unrealized Gain	2	3
Unrealized Loss	(23)	(19)
Estimated Fair Value	6,895	5,468
Cash equivalents	3,789	436
Marketable Securities	3,106	5,032
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	851
Fair value, unrealized loss greater than 12 months	2,065
Fair value with unrealized loss, total	2,916
Unrealized loss position, aggregate losses
Unrealized loss, less than 12 months, gross	(4)
Unrealized loss, 12 months or greater, gross	(19)
Gross unrealized loss, total	(23)
Amortized Cost Basis
Less than one year	5,381	2,209
Due in 1-5 years	1,500	3,210
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date	35	65
Total	6,916	5,484
Estimated Fair Value
Less than one year	5,375	2,209
Due in 1-5 years	1,485	3,194
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date	35	65
Total	6,895	5,468
Money market funds
Classified as:
Amortized cost	3,789	321
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	3,789	321
Cash equivalents	3,789	321
Marketable Securities	0	0
Corporate debt securities
Classified as:
Amortized cost	1,304	2,397
Unrealized Gain	0	1
Unrealized Loss	(9)	(10)
Estimated Fair Value	1,295	2,388
Cash equivalents	0	33
Marketable Securities	1,295	2,355
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	433
Fair value, unrealized loss greater than 12 months	801
Fair value with unrealized loss, total	1,234
Unrealized loss position, aggregate losses
Unrealized loss, less than 12 months, gross	(2)
Unrealized loss, 12 months or greater, gross	(7)
Gross unrealized loss, total	(9)
Debt securities of United States government agencies
Classified as:
Amortized cost	822	1,193
Unrealized Gain	0	0
Unrealized Loss	(7)	(5)
Estimated Fair Value	815	1,188
Cash equivalents	0	27
Marketable Securities	815	1,161
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	175
Fair value, unrealized loss greater than 12 months	640
Fair value with unrealized loss, total	815
Unrealized loss position, aggregate losses
Unrealized loss, less than 12 months, gross	(1)
Unrealized loss, 12 months or greater, gross	(6)
Gross unrealized loss, total	(7)
Debt securities issued by the United States Treasury
Classified as:
Amortized cost	577	852
Unrealized Gain	0	0
Unrealized Loss	(4)	(2)
Estimated Fair Value	573	850
Cash equivalents	0	55
Marketable Securities	573	795
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	170
Fair value, unrealized loss greater than 12 months	404
Fair value with unrealized loss, total	574
Unrealized loss position, aggregate losses
Unrealized loss, less than 12 months, gross	(1)
Unrealized loss, 12 months or greater, gross	(3)
Gross unrealized loss, total	(4)
Asset-backed securities
Classified as:
Amortized cost	254	490
Unrealized Gain	0	0
Unrealized Loss	(2)	(1)
Estimated Fair Value	252	489
Cash equivalents	0	0
Marketable Securities	252	489
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	73
Fair value, unrealized loss greater than 12 months	179
Fair value with unrealized loss, total	252
Unrealized loss position, aggregate losses
Unrealized loss, less than 12 months, gross	0
Unrealized loss, 12 months or greater, gross	(2)
Gross unrealized loss, total	(2)
Mortgage-backed securities issued by United States government-sponsored enterprises
Classified as:
Amortized cost	128	161
Unrealized Gain	2	2
Unrealized Loss	0	(1)
Estimated Fair Value	130	162
Cash equivalents	0	0
Marketable Securities	130	162
Foreign government bonds
Classified as:
Amortized cost	42	70
Unrealized Gain	0	0
Unrealized Loss	(1)	0
Estimated Fair Value	41	70
Cash equivalents	0	0
Marketable Securities	41	$ 70
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	0
Fair value, unrealized loss greater than 12 months	41
Fair value with unrealized loss, total	41
Unrealized loss position, aggregate losses
Unrealized loss, less than 12 months, gross	0
Unrealized loss, 12 months or greater, gross	(1)
Gross unrealized loss, total	$ (1)