Marketable Securities (Details) - USD ($) $ in Millions	Apr. 30, 2017	Jan. 29, 2017
Summary of cash equivalents and marketable securities:
Amortized Cost	$ 4,271	$ 5,484
Unrealized Gain	3	3
Unrealized Loss	(16)	(19)
Classified as:
Cash equivalents	41	436
Marketable securities	4,217	5,032
Total cash equivalents and marketable securities	4,258	5,468
Amortized Cost
Less than one year	1,353	2,209
Due in 1-5 years	2,853	3,210
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date	65	65
Total	4,271	5,484
Estimated Fair Value
Less than one year	1,353	2,209
Due in 1-5 years	2,840	3,194
Mortgage-backed securities issued by United States government-sponsored enterprises not due to a single maturity date	65	65
Total	4,258	5,468
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	3,449
Fair value, unrealized loss greater than 12 months	71
Fair value with unrealized loss, total	3,520
Unrealized Loss Position, Aggregate Losses
Unrealized loss, less than 12 months, gross	(15)
Unrealized loss, 12 months or greater, gross	(1)
Gross unrealized loss, total	(16)
Corporate debt securities
Summary of cash equivalents and marketable securities:
Amortized Cost	1,866	2,397
Unrealized Gain	1	1
Unrealized Loss	(7)	(10)
Classified as:
Cash equivalents	0	33
Marketable securities	1,860	2,355
Total cash equivalents and marketable securities	1,860	2,388
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	1,390
Fair value, unrealized loss greater than 12 months	18
Fair value with unrealized loss, total	1,408
Unrealized Loss Position, Aggregate Losses
Unrealized loss, less than 12 months, gross	(7)
Unrealized loss, 12 months or greater, gross	0
Gross unrealized loss, total	(7)
Debt securities of United States government agencies
Summary of cash equivalents and marketable securities:
Amortized Cost	1,067	1,193
Unrealized Gain	0	0
Unrealized Loss	(5)	(5)
Classified as:
Cash equivalents	0	27
Marketable securities	1,062	1,161
Total cash equivalents and marketable securities	1,062	1,188
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	984
Fair value, unrealized loss greater than 12 months	17
Fair value with unrealized loss, total	1,001
Unrealized Loss Position, Aggregate Losses
Unrealized loss, less than 12 months, gross	(5)
Unrealized loss, 12 months or greater, gross	0
Gross unrealized loss, total	(5)
Debt securities issued by the United States Treasury
Summary of cash equivalents and marketable securities:
Amortized Cost	683	852
Unrealized Gain	0	0
Unrealized Loss	(2)	(2)
Classified as:
Cash equivalents	0	55
Marketable securities	681	795
Total cash equivalents and marketable securities	681	850
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	669
Fair value, unrealized loss greater than 12 months	0
Fair value with unrealized loss, total	669
Unrealized Loss Position, Aggregate Losses
Unrealized loss, less than 12 months, gross	(2)
Unrealized loss, 12 months or greater, gross	0
Gross unrealized loss, total	(2)
Asset-backed Securities
Summary of cash equivalents and marketable securities:
Amortized Cost	381	490
Unrealized Gain	0	0
Unrealized Loss	(1)	(1)
Classified as:
Cash equivalents	0	0
Marketable securities	380	489
Total cash equivalents and marketable securities	380	489
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	355
Fair value, unrealized loss greater than 12 months	0
Fair value with unrealized loss, total	355
Unrealized Loss Position, Aggregate Losses
Unrealized loss, less than 12 months, gross	(1)
Unrealized loss, 12 months or greater, gross	0
Gross unrealized loss, total	(1)
Mortgage backed securities issued by United States government-sponsored enterprises
Summary of cash equivalents and marketable securities:
Amortized Cost	169	161
Unrealized Gain	2	2
Unrealized Loss	(1)	(1)
Classified as:
Cash equivalents	0	0
Marketable securities	170	162
Total cash equivalents and marketable securities	170	162
Fair value, unrealized loss position
Fair value, unrealized loss less than 12 months	51
Fair value, unrealized loss greater than 12 months	36
Fair value with unrealized loss, total	87
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)
Foreign government bonds
Summary of cash equivalents and marketable securities:
Amortized Cost	64	70
Unrealized Gain	0	0
Unrealized Loss	0	0
Classified as:
Cash equivalents	0	0
Marketable securities	64	70
Total cash equivalents and marketable securities	64	70
Money market funds
Summary of cash equivalents and marketable securities:
Amortized Cost	41	321
Unrealized Gain	0	0
Unrealized Loss	0	0
Classified as:
Cash equivalents	41	321
Marketable securities	0	0
Total cash equivalents and marketable securities	$ 41	$ 321