Marketable Securities (Tables)

12 Months Ended

Jan. 27, 2019

Investments, Debt and Equity Securities [Abstract]

Schedule of cash equivalents and marketable securities

The following is a summary of cash equivalents and marketable securities as of January 27, 2019 and January 28, 2018:

	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

	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 amortized cost and estimated fair value of cash equivalents and marketable securities as of January 27, 2019 and January 28, 2018 are shown below by contractual maturity.

	January 27, 2019				January 28, 2018
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(In millions)
Less than one year	$	5,042	$	5,034	$	5,381	$	5,375
Due in 1 - 5 years	2,271		2,268		1,500		1,485
Mortgage-backed securities issued by United States government-sponsored enterprises not due at a single maturity date	22		22		35		35
Total	$	7,335	$	7,324	$	6,916	$	6,895

The following table provides the breakdown of unrealized losses as of January 27, 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	$	1,674	$	(1	)	$	401	$	(3	)	$	2,075	$	(4	)
Corporate debt securities	915		(3		)	649		(3		)	1,564		(6		)
Debt securities issued by the United States Treasury	1,015		—			161		(1		)	1,176		(1		)
Asset-backed securities	—		—			151		(1		)	151		(1		)
Total	$	3,604	$	(4	)	$	1,362	$	(8	)	$	4,966	$	(12	)