Marketable Securities (Details) (USD $)	12 Months Ended
	Jan. 29, 2012	Jan. 30, 2011	Jan. 31, 2010
Summary of cash equivalents and marketable securities:
Amortized Cost	$ 2,864,755,000	$ 2,165,536,000
Unrealized Gain	11,998,000	10,926,000
Unrealized Loss	(487,000)	(473,000)
Estimated Fair Value	2,876,266,000	2,175,989,000
Classified as:
Cash equivalents	414,566,000	350,787,000
Marketable securities	2,461,700,000	1,825,202,000
Total cash equivalents and marketable securities	2,876,266,000	2,175,989,000
Amortized Cost Basis [Abstract]
Less than one year	1,705,916,000	1,176,046,000
Due in 1-5 years	1,047,956,000	899,993,000
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date	110,883,000	89,497,000
Total	2,864,755,000	2,165,536,000
Estimated Fair Value [Abstract]
Less than one year	1,708,154,000	1,178,733,000
Due in 1-5 years	1,053,265,000	904,926,000
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date	114,847,000	92,330,000
Total	2,876,266,000	2,175,989,000
Net realized gain	400,000	1,500,000	1,800,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,417,422,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,168,112,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,585,534,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(162,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(325,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(487,000)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	11
Available For Sale Securities Net Unrealized Gain Loss	11,500,000	10,500,000
US Government Agencies Debt Securities [Member]
Summary of cash equivalents and marketable securities:
Amortized Cost	769,300,000	531,789,000
Unrealized Gain	1,605,000	1,034,000
Unrealized Loss	(151,000)	(226,000)
Estimated Fair Value	770,754,000	532,597,000
Classified as:
Total cash equivalents and marketable securities	770,754,000	532,597,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	475,024,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	295,730,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	770,754,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(79,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(72,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(151,000)
US Treasury Securities [Member]
Summary of cash equivalents and marketable securities:
Amortized Cost	533,616,000	435,091,000
Unrealized Gain	2,161,000	1,939,000
Unrealized Loss	(3,000)	(18,000)
Estimated Fair Value	535,774,000	437,012,000
Classified as:
Total cash equivalents and marketable securities	535,774,000	437,012,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	266,203,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	269,571,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	535,774,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(1,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(2,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(3,000)
Corporate Debt Securities [Member]
Summary of cash equivalents and marketable securities:
Amortized Cost	1,114,439,000	925,226,000
Unrealized Gain	3,268,000	3,354,000
Unrealized Loss	(260,000)	(208,000)
Estimated Fair Value	1,117,447,000	928,372,000
Classified as:
Total cash equivalents and marketable securities	1,117,447,000	928,372,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	672,554,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	444,893,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,117,447,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(82,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(178,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(260,000)
Mortgage backed securities issued by United Sates government-sponsored enterprises
Summary of cash equivalents and marketable securities:
Amortized Cost	156,668,000	140,844,000
Unrealized Gain	4,964,000	4,599,000
Unrealized Loss	(73,000)	(21,000)
Estimated Fair Value	161,559,000	145,422,000
Classified as:
Total cash equivalents and marketable securities	161,559,000	145,422,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	3,641,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	157,918,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	161,559,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(73,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(73,000)
Money Market Funds [Member]
Summary of cash equivalents and marketable securities:
Amortized Cost	290,732,000	132,586,000
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	290,732,000	132,586,000
Classified as:
Total cash equivalents and marketable securities	$ 290,732,000	$ 132,586,000