v2.4.0.6

Investments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified |  |  | 6 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jan. 28, 2012 | Jul. 30, 2011 | Jan. 28, 2012 Auction rate securities | Jan. 28, 2012 Available-for-sale investments - non-current | Jul. 30, 2011 Available-for-sale investments - non-current | Jan. 28, 2012 Available-for-sale investments - non-current Auction rate securities | Jul. 30, 2011 Available-for-sale investments - non-current Auction rate securities
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |  |  |
Available-for-sale investments, Total | $ 198.7 | $ 192.6 |  | $ 144.0 | $ 138.5 | $ 8.9 | $ 12.0
Available-for-sale investments, called for redemption |  |  | $ 3.4 |  |  |  |

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