Marketable Securities (Tables)

12 Months Ended

Jan. 28, 2018

Notes to financial statements [Abstract]

Cash Equivalents and Marketable Securities

	January 28, 2018
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value		Reported as
										Cash Equivalents		Marketable Securities
	(In millions)
Money market funds	$	3,789	$	—	$	—		$	3,789	$	3,789	$	—
Corporate debt securities	1,304		—		(9		)	1,295		—		1,295
Debt securities of United States government agencies	822		—		(7		)	815		—		815
Debt securities issued by the United States Treasury	577		—		(4		)	573		—		573
Asset-backed securities	254		—		(2		)	252		—		252
Mortgage-backed securities issued by United States government-sponsored enterprises	128		2		—			130		—		130
Foreign government bonds	42		—		(1		)	41		—		41
Total	$	6,916	$	2	$	(23	)	$	6,895	$	3,789	$	3,106

	January 29, 2017
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value		Reported as
										Cash Equivalents		Marketable Securities
	(In millions)
Corporate debt securities	$	2,397	$	1	$	(10	)	$	2,388	$	33	$	2,355
Debt securities of United States government agencies	1,193		—		(5		)	1,188		27		1,161
Debt securities issued by the United States Treasury	852		—		(2		)	850		55		795
Asset-backed securities	490		—		(1		)	489		—		489
Money market funds	321		—		—			321		321		—
Mortgage backed securities issued by United States government-sponsored enterprises	161		2		(1		)	162		—		162
Foreign government bonds	70		—		—			70		—		70
Total	$	5,484	$	3	$	(19	)	$	5,468	$	436	$	5,032

Schedule of Unrealized Loss on Investments

	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
	(In millions)
Corporate debt securities	$	433	$	(2	)	$	801	$	(7	)	$	1,234	$	(9	)
Debt securities issued by United States government agencies	175		(1		)	640		(6		)	815		(7		)
Debt securities issued by the US Treasury	170		(1		)	404		(3		)	574		(4		)
Asset-backed securities	73		—			179		(2		)	252		(2		)
Foreign government bonds	—		—			41		(1		)	41		(1		)
Total	$	851	$	(4	)	$	2,065	$	(19	)	$	2,916	$	(23	)

Schedule of Amortization Cost and Estimated FV of CE and MS

	January 28, 2018				January 29, 2017
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(In millions)
Less than one year	$	5,381	$	5,375	$	2,209	$	2,209
Due in 1 - 5 years	1,500		1,485		3,210		3,194
Mortgage-backed securities issued by government-sponsored enterprises not due at a single maturity date	35		35		65		65
Total	$	6,916	$	6,895	$	5,484	$	5,468