Marketable Securities (Tables)

9 Months Ended

Oct. 28, 2018

Investments, Debt and Equity Securities [Abstract]

Cash Equivalents and Marketable Securities

The following is a summary of cash equivalents and marketable securities as of October 28, 2018 and January 28, 2018:

	October 28, 2018
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value		Reported as
										Cash Equivalents		Marketable Securities
	(In millions)
Corporate debt securities	$	2,732	$	1	$	(6	)	$	2,727	$	—	$	2,727
Debt securities of United States government agencies	2,140		—		(5		)	$	2,135	—		2,135
Debt securities issued by the United States Treasury	1,544		—		(2		)	1,542		—		1,542
Money market funds	602		—		—			602		602		—
Foreign government bonds	191		—		—			191		—		191
Asset-backed securities	178		—		(2		)	176		—		176
Mortgage-backed securities issued by United States government-sponsored enterprises	98		1		—			99		—		99
Total	$	7,485	$	2	$	(15	)	$	7,472	$	602	$	6,870

	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

The following table provides the breakdown of unrealized losses as of October 28, 2018, aggregated by investment category and length of time that individual securities have been in a continuous loss position: 

	Less than 12 Months					12 Months or Greater					Total
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
	(In millions)
Debt securities issued by United States government agencies	$	1,584	$	(1	)	$	507	$	(4	)	$	2,091	$	(5	)
Debt securities issued by the United States Treasury	1,253		—			289		(2		)	1,542		(2		)
Corporate debt securities	167		—			794		(6		)	961		(6		)
Asset-backed securities	—		—			176		(2		)	176		(2		)
Total	$	3,004	$	(1	)	$	1,766	$	(14	)	$	4,770	$	(15	)

The amortized cost and estimated fair value of cash equivalents and marketable securities as of October 28, 2018 and January 28, 2018 are shown below by contractual maturity.  

	October 28, 2018				January 28, 2018
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(In millions)
Less than 1 year	$	5,537	$	5,524	$	5,381	$	5,375
Due in 1 - 5 years	1,923		1,923		1,500		1,485
Mortgage-backed securities issued by United States government-sponsored enterprises not due at a single maturity date	25		25		35		35
Total	$	7,485	$	7,472	$	6,916	$	6,895