Fair Value of Cash Equivalents and Marketable Securities (Details) (USD $)	Oct. 28, 2012		Jan. 29, 2012
Financial assets and liabilities measured at fair value:
Estimated Fair Value	$ 3,010,411,000		$ 2,876,266,000
Cash equivalents of corporate debt securities	16,000,000
Marketable securities of corporate debt securities	1,175,700,000
Estimate of Fair Value
Financial assets and liabilities measured at fair value:
Total cash equivalents and marketable securities	3,010,411,000
Quoted Price in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities measured at fair value:
Money market funds	85,030,000	[1]
Total cash equivalents and marketable securities	85,030,000
Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value:
Debt securities issued by US Government agencies	847,596,000	[2]
Debt securities issued by United States Treasury	695,466,000	[2]
Corporate debt securities	1,191,658,000	[3]
Mortgage-backed securitieis issued by Government-sponsored entities	190,661,000	[2]
Money market funds	0
Total cash equivalents and marketable securities	2,925,381,000
US Government Agencies Debt Securities [Member]
Financial assets and liabilities measured at fair value:
Estimated Fair Value	847,596,000		770,754,000
US Treasury Securities [Member]
Financial assets and liabilities measured at fair value:
Estimated Fair Value	695,466,000		535,774,000
Corporate Debt Securities [Member]
Financial assets and liabilities measured at fair value:
Estimated Fair Value	1,191,658,000		1,117,447,000
Money Market Funds [Member]
Financial assets and liabilities measured at fair value:
Estimated Fair Value	85,030,000		290,732,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Financial assets and liabilities measured at fair value:
Estimated Fair Value	$ 190,661,000		$ 161,559,000

[1] Included in Cash Equivalents on the Condensed Consolidated Balance Sheet.

[2] Included in Marketable Securities on the Condensed Consolidated Balance Sheet.

[3] Includes $16.0 million in Cash Equivalents and $1,175.7 million in Marketable Securities on the Condensed Consolidated Balance Sheet.