Marketable Securities (Details) (USD $)	12 Months Ended
	Jan. 27, 2013	Jan. 29, 2012	Jan. 30, 2011
Summary of cash equivalents and marketable securities:
Amortized Cost	$ 3,286,436,000	$ 2,864,755,000
Unrealized Gain	11,670,000	11,998,000
Unrealized Loss	(843,000)	(487,000)
Estimated Fair Value	3,297,263,000	2,876,266,000
Classified as:
Cash equivalents	302,166,000	414,566,000
Marketable securities	2,995,097,000	2,461,700,000
Total cash equivalents and marketable securities	3,297,263,000	2,876,266,000
Amortized Cost Basis [Abstract]
Less than one year	1,397,350,000	1,705,916,000
Due in 1-5 years	1,777,785,000	1,047,956,000
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date	111,301,000	110,883,000
Total	3,286,436,000	2,864,755,000
Estimated Fair Value [Abstract]
Less than one year	1,399,304,000	1,708,154,000
Due in 1-5 years	1,783,103,000	1,053,265,000
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date	114,856,000	114,847,000
Total	3,297,263,000	2,876,266,000
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	1,203,515,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,897,958,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,101,473,000
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	(73,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(770,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(843,000)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	9
Net realized gain	500,000	400,000	1,500,000
Available For Sale Securities Net Unrealized Gain Loss	10,900,000	11,500,000
US Government Agencies Debt Securities [Member]
Summary of cash equivalents and marketable securities:
Amortized Cost	867,087,000	769,300,000
Unrealized Gain	1,199,000	1,605,000
Unrealized Loss	(139,000)	(151,000)
Estimated Fair Value	868,147,000	770,754,000
Classified as:
Total cash equivalents and marketable securities	868,147,000	770,754,000
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	355,378,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	512,769,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	868,147,000
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	(23,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(116,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(139,000)
US Treasury Securities [Member]
Summary of cash equivalents and marketable securities:
Amortized Cost	785,228,000	533,616,000
Unrealized Gain	1,102,000	2,161,000
Unrealized Loss	(105,000)	(3,000)
Estimated Fair Value	786,225,000	535,774,000
Classified as:
Total cash equivalents and marketable securities	786,225,000	535,774,000
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	278,383,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	507,842,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	786,225,000
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	(15,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(90,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(105,000)
Corporate Debt Securities [Member]
Summary of cash equivalents and marketable securities:
Amortized Cost	1,255,297,000	1,114,439,000
Unrealized Gain	3,175,000	3,268,000
Unrealized Loss	(542,000)	(260,000)
Estimated Fair Value	1,257,930,000	1,117,447,000
Classified as:
Total cash equivalents and marketable securities	1,257,930,000	1,117,447,000
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	563,842,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	694,088,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,257,930,000
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	(35,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(507,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(542,000)
Mortgage backed securities issued by United Sates government-sponsored enterprises
Summary of cash equivalents and marketable securities:
Amortized Cost	183,034,000	156,668,000
Unrealized Gain	6,194,000	4,964,000
Unrealized Loss	(57,000)	(73,000)
Estimated Fair Value	189,171,000	161,559,000
Classified as:
Total cash equivalents and marketable securities	189,171,000	161,559,000
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	5,912,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	183,259,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	189,171,000
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	(57,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(57,000)
Money Market Funds
Summary of cash equivalents and marketable securities:
Amortized Cost	195,790,000	290,732,000
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	195,790,000	290,732,000
Classified as:
Total cash equivalents and marketable securities	$ 195,790,000	$ 290,732,000