Marketable Securities (Tables)

3 Months Ended

Apr. 28, 2019

Investments, Debt and Equity Securities [Abstract]

Cash Equivalents and Marketable Securities

The following is a summary of cash equivalents and marketable securities as of April 28, 2019 and January 27, 2019:

	April 28, 2019
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value		Reported as
										Cash Equivalents		Marketable Securities
	(In millions)
Corporate debt securities	$	2,899	$	2	$	(2	)	$	2,899	$	1,048	$	1,851
Debt securities of United States government agencies	1,882		—		(1		)	1,881		—		1,881
Debt securities issued by the United States Treasury	1,833		—		—			1,833		932		901
Money market funds	681		—		—			681		681		—
Foreign government bonds	183		—		—			183		—		183
Asset-backed securities	133		—		(1		)	132		—		132
Mortgage-backed securities issued by United States government-sponsored enterprises	81		1		—			82		—		82
Total	$	7,692	$	3	$	(4	)	$	7,691	$	2,661	$	5,030

	January 27, 2019
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value		Reported as
										Cash Equivalents		Marketable Securities
	(In millions)
Corporate debt securities	$	2,626	$	—	$	(6	)	$	2,620	$	25	$	2,595
Debt securities of United States government agencies	2,284		—		(4		)	2,280		—		2,280
Debt securities issued by the United States Treasury	1,493		—		(1		)	1,492		176		1,316
Money market funds	483		—		—			483		483		—
Foreign government bonds	209		—		—			209		—		209
Asset-backed securities	152		—		(1		)	151		—		151
Mortgage-backed securities issued by United States government-sponsored enterprises	88		1		—			89		—		89
Total	$	7,335	$	1	$	(12	)	$	7,324	$	684	$	6,640

The following table provides the breakdown of unrealized losses as of April 28, 2019, 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	$	1,429	$	—		$	306	$	(1	)	$	1,735	$	(1	)
Corporate debt securities	330		(1		)	453		(1		)	783		(2		)
Asset-backed securities	—		—			132		(1		)	132		(1		)
Total	$	1,759	$	(1	)	$	891	$	(3	)	$	2,650	$	(4	)

The amortized cost and estimated fair value of cash equivalents and marketable securities as of April 28, 2019 and January 27, 2019 are shown below by contractual maturity.  

	April 28, 2019				January 27, 2019
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(In millions)
Less than 1 year	$	5,773	$	5,770	$	5,042	$	5,034
Due in 1 - 5 years	1,896		1,898		2,271		2,268
Mortgage-backed securities issued by United States government-sponsored enterprises not due at a single maturity date	23		23		22		22
Total	$	7,692	$	7,691	$	7,335	$	7,324