Marketable Securities (Tables)

9 Months Ended

Oct. 25, 2015

Schedule of Available-for-sale Securities [Line Items]

Cash Equivalents and Marketable Securities

	October 25, 2015
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
	(In millions)
Corporate debt securities	$	1,975	$	2	$	(2	)	$	1,975
Debt securities of U.S. government agencies	994		1		—			995
Debt securities issued by the U.S. Treasury	554		1		—			555
Asset-backed securities	472		—		—			472
Mortgage-backed securities issued by U.S. government-sponsored enterprises	240		4		(1		)	243
Foreign government bonds	83		—		—			83
Money market funds	30		—		—			30
Total	$	4,348	$	8	$	(3	)	$	4,353
Classified as:
Cash equivalents								$	96
Marketable securities								4,257
Total								$	4,353

	January 25, 2015
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
	(In millions)
Corporate debt securities	$	2,185	$	2	$	(1	)	$	2,186
Debt securities of U.S. government agencies	750		1		(1		)	750
Debt securities issued by the U.S. Treasury	534		3		—			537
Asset-backed securities	453		—		—			453
Mortgage-backed securities issued by U.S. government-sponsored enterprises	274		5		(1		)	278
Foreign government bonds	85		—		—			85
Money market funds	132		—		—			132
Total	$	4,413	$	11	$	(3	)	$	4,421
Classified as:
Cash equivalents								$	295
Marketable securities								4,126
Total								$	4,421

Schedule of Unrealized Loss on Investments [Table Text Block]

	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	$	798	$	(2	)	$	54	$	—	$	852	$	(2	)
Mortgage-backed securities issued by U.S. government-sponsored enterprises	73		(1		)	26		—		99		(1		)
Total	$	871	$	(3	)	$	80	$	—	$	951	$	(3	)

Schedule of Cash Equivalents and Marketable Securities Available for Sale

	October 25, 2015				January 25, 2015
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(In millions)
Less than 1 year	$	1,453	$	1,454	$	1,570	$	1,571
Due in 1 - 5 years	2,811		2,815		2,720		2,726
Mortgage-backed securities issued by government-sponsored enterprises not due at a single maturity date	84		84		123		124
Total	$	4,348	$	4,353	$	4,413	$	4,421