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Fair Value Measurements - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified |
Jan. 28, 2012
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Jul. 30, 2011
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|---|---|---|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Amount by which fair value of available-for-sale securities is lower than cost basis | $ 2.0 | $ 2.4 |