Marketable Securities (Tables)

12 Months Ended

Jan. 29, 2012

Notes to financial statements [Abstract]

Cash Equivalents and Marketable Securities

	January 29, 2012
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
	(In thousands)
Debt securities of United States government agencies	$	769,300	$	1,605	$	(151	)	$	770,754
Corporate debt securities	1,114,439		3,268		(260		)	1,117,447
Mortgage backed securities issued by United States government-sponsored enterprises	156,668		4,964		(73		)	161,559
Money market funds	290,732		—		—			290,732
Debt securities issued by United States Treasury	533,616		2,161		(3		)	535,774
Total	$	2,864,755	$	11,998	$	(487	)	$	2,876,266
Classified as:
Cash equivalents								$	414,566
Marketable securities								2,461,700
Total								$	2,876,266

	January 30, 2011
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
	(In thousands)
Debt securities of United States government agencies	$	531,789	$	1,034	$	(226	)	$	532,597
Corporate debt securities	925,226		3,354		(208		)	928,372
Mortgage backed securities issued by United States government-sponsored enterprises	140,844		4,599		(21		)	145,422
Money market funds	132,586		—		—			132,586
Debt securities issued by United States Treasury	435,091		1,939		(18		)	437,012
Total	$	2,165,536	$	10,926	$	(473	)	$	2,175,989
Classified as:
Cash equivalents								$	350,787
Marketable securities								1,825,202
Total								$	2,175,989

The following table provides the breakdown of the investments with unrealized losses at January 29, 2012:

	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	$	672,554	$	(82	)	$	444,893	$	(178	)	$	1,117,447	$	(260	)
Mortgage backed securities issued by United States government-sponsored enterprises	3,641		—			157,918		(73		)	161,559		(73		)
Debt securities of United States Treasury	266,203		(1		)	269,571		(2		)	535,774		(3		)
Debt securities issued by United States government agencies	475,024		(79		)	295,730		(72		)	770,754		(151		)
Total	$	1,417,422	$	(162	)	$	1,168,112	$	(325	)	$	2,585,534	$	(487	)

Schedule of Cash Equivalents and Marketable Securities Available for Sale

	January 29, 2012				January 30, 2011
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(In thousands)
Less than one year	$	1,705,916	$	1,708,154	$	1,176,046	$	1,178,733
Due in 1 - 5 years	1,047,956		1,053,265		899,993		904,926
Mortgage-backed securities issued by government-sponsored enterprises not due at a single maturity date	110,883		114,847		89,497		92,330
Total	$	2,864,755	$	2,876,266	$	2,165,536	$	2,175,989