Marketable Securities (Details) (USD $) | 3 Months Ended | 9 Months Ended | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Oct. 30, 2011 | Oct. 31, 2010 | Oct. 30, 2011 | Oct. 31, 2010 | Jan. 30, 2011 | |||||||||||||
| Summary of cash equivalents and marketable securities: | |||||||||||||||||
| Amortized Cost | $ 2,320,984,000 | $ 2,320,984,000 | $ 2,165,536,000 | ||||||||||||||
| Unrealized Gain | 10,998,000 | 10,998,000 | 10,926,000 | ||||||||||||||
| Unrealized Loss | (1,397,000) | (1,397,000) | (473,000) | ||||||||||||||
| Estimated Fair Value | 2,330,585,000 | 2,330,585,000 | 2,175,989,000 | ||||||||||||||
| Classified as: | |||||||||||||||||
| Cash equivalents | 149,047,000 | 149,047,000 | 350,787,000 | ||||||||||||||
| Marketable securities | 2,181,538,000 | 2,181,538,000 | 1,825,202,000 | ||||||||||||||
| Total cash equivalents and marketable securities | 2,330,585,000 | 2,330,585,000 | 2,175,989,000 | ||||||||||||||
| Schedule of Cash Equivalents and Marketable Securities Available for Sale [Abstract] | |||||||||||||||||
| Less than one year | 1,236,291,000 | 1,236,291,000 | 1,176,046,000 | ||||||||||||||
| Due in 1-5 years | 984,387,000 | 984,387,000 | 899,993,000 | ||||||||||||||
| Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date | 100,306,000 | 100,306,000 | 89,497,000 | ||||||||||||||
| Estimated Fair Value | |||||||||||||||||
| Less than one year | 1,237,962,000 | 1,237,962,000 | 1,178,733,000 | ||||||||||||||
| Due in 1-5 years | 988,574,000 | 988,574,000 | 904,926,000 | ||||||||||||||
| Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date | 104,049,000 | 104,049,000 | 92,330,000 | ||||||||||||||
| Net realized gain | 100,000 | 300,000 | 500,000 | 1,300,000 | |||||||||||||
Debt securities of United States government agencies | |||||||||||||||||
| Summary of cash equivalents and marketable securities: | |||||||||||||||||
| Amortized Cost | 607,828,000 | 607,828,000 | 531,789,000 | ||||||||||||||
| Unrealized Gain | 1,134,000 | 1,134,000 | 1,034,000 | ||||||||||||||
| Unrealized Loss | (330,000) | (330,000) | (226,000) | ||||||||||||||
| Estimated Fair Value | 608,632,000 | [1] | 608,632,000 | [1] | 532,597,000 | ||||||||||||
| Classified as: | |||||||||||||||||
| Total cash equivalents and marketable securities | 608,632,000 | [1] | 608,632,000 | [1] | 532,597,000 | ||||||||||||
Debt securities issued by United States Treasury | |||||||||||||||||
| Summary of cash equivalents and marketable securities: | |||||||||||||||||
| Amortized Cost | 430,233,000 | 430,233,000 | 435,091,000 | ||||||||||||||
| Unrealized Gain | 2,019,000 | 2,019,000 | 1,939,000 | ||||||||||||||
| Unrealized Loss | (505,000) | (505,000) | (18,000) | ||||||||||||||
| Estimated Fair Value | 431,747,000 | [2] | 431,747,000 | [2] | 437,012,000 | ||||||||||||
| Classified as: | |||||||||||||||||
| Total cash equivalents and marketable securities | 431,747,000 | [2] | 431,747,000 | [2] | 437,012,000 | ||||||||||||
Corporate debt securities | |||||||||||||||||
| Summary of cash equivalents and marketable securities: | |||||||||||||||||
| Amortized Cost | 1,105,438,000 | 1,105,438,000 | 925,226,000 | ||||||||||||||
| Unrealized Gain | 2,840,000 | 2,840,000 | 3,354,000 | ||||||||||||||
| Unrealized Loss | (531,000) | (531,000) | (208,000) | ||||||||||||||
| Estimated Fair Value | 1,107,747,000 | [3] | 1,107,747,000 | [3] | 928,372,000 | ||||||||||||
| Classified as: | |||||||||||||||||
| Total cash equivalents and marketable securities | 1,107,747,000 | [3] | 1,107,747,000 | [3] | 928,372,000 | ||||||||||||
Mortgage backed securities issued by United Sates government-sponsored enterprises | |||||||||||||||||
| Summary of cash equivalents and marketable securities: | |||||||||||||||||
| Amortized Cost | 141,189,000 | 141,189,000 | 140,844,000 | ||||||||||||||
| Unrealized Gain | 5,005,000 | 5,005,000 | 4,599,000 | ||||||||||||||
| Unrealized Loss | (31,000) | (31,000) | (21,000) | ||||||||||||||
| Estimated Fair Value | 146,163,000 | [4] | 146,163,000 | [4] | 145,422,000 | ||||||||||||
| Classified as: | |||||||||||||||||
| Total cash equivalents and marketable securities | 146,163,000 | [4] | 146,163,000 | [4] | 145,422,000 | ||||||||||||
Money market funds | |||||||||||||||||
| Summary of cash equivalents and marketable securities: | |||||||||||||||||
| Amortized Cost | 36,296,000 | 36,296,000 | 132,586,000 | ||||||||||||||
| Unrealized Gain | 0 | ||||||||||||||||
| Unrealized Loss | 0 | ||||||||||||||||
| Estimated Fair Value | 36,296,000 | [5] | 36,296,000 | [5] | 132,586,000 | ||||||||||||
| Classified as: | |||||||||||||||||
| Total cash equivalents and marketable securities | $ 36,296,000 | [5] | $ 36,296,000 | [5] | $ 132,586,000 | ||||||||||||
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