Marketable Securities (Tables)

6 Months Ended

Jul. 27, 2014

Notes to financial statements [Abstract]

Cash Equivalents and Marketable Securities

	July 27, 2014
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
	(In thousands)
Corporate debt securities	$	2,042,721	$	2,139	$	(1,430	)	$	2,043,430
Debt securities of United States government agencies	700,025		352		(216		)	700,161
Debt securities issued by United States Treasury	586,484		896		(69		)	587,311
Asset-backed securities	411,669		169		(310		)	411,528
Mortgage-backed securities issued by United States government-sponsored enterprises	258,483		4,279		(1,340		)	261,422
Money market funds	119,491		—		—			119,491
Total	$	4,118,873	$	7,835	$	(3,365	)	$	4,123,343
Classified as:
Cash equivalents								$	252,381
Marketable securities								3,870,962
Total								$	4,123,343

	January 26, 2014
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
	(In thousands)
Corporate debt securities	$	1,827,788	$	1,857	$	(1,065	)	$	1,828,580
Debt securities of United States government agencies	1,012,740		848		(261		)	1,013,327
Debt securities issued by United States Treasury	495,889		621		(57		)	496,453
Money market funds	307,865		—		—			307,865
Asset-backed securities	258,017		15		(315		)	257,717
Mortgage-backed securities issued by United States government-sponsored enterprises	185,594		3,837		(725		)	188,706
Total	$	4,087,893	$	7,178	$	(2,423	)	$	4,092,648
Classified as:
Cash equivalents								$	572,425
Marketable securities								3,520,223
Total								$	4,092,648

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 thousands)
Corporate debt securities	$	664,945	$	(90	)	$	1,378,485	$	(1,340	)	$	2,043,430	$	(1,430	)
Debt securities of United States government agencies	304,481		(3		)	395,680		(213		)	700,161		(216		)
Debt securities issued by United States Treasury	45,045		(28		)	542,266		(41		)	587,311		(69		)
Asset-backed securities	162,899		(14		)	248,629		(296		)	411,528		(310		)
Mortgage-backed securities issued by United States government-sponsored enterprises	—		—			261,422		(1,340		)	261,422		(1,340		)
Total	$	1,177,370	$	(135	)	$	2,826,482	$	(3,230	)	$	4,003,852	$	(3,365	)

Schedule of Cash Equivalents and Marketable Securities Available for Sale

	July 27, 2014				January 26, 2014
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(In thousands)
Less than 1 year	$	1,296,254	$	1,296,861	$	1,883,132	$	1,883,753
Due in 1 - 5 years	2,665,096		2,667,222		2,114,289		2,117,387
Mortgage-backed securities issued by government-sponsored enterprises not due at a single maturity date	157,523		159,260		90,472		91,508
Total	$	4,118,873	$	4,123,343	$	4,087,893	$	4,092,648