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Employee and Director Stock Plans - Summary of Restricted Stock Award and Restricted Stock Unit Activity (Detail) (USD $)
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12 Months Ended | |||||
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Jan. 31, 2014
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Jan. 31, 2013
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Jan. 31, 2012
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Restricted Stock Units (RSUs) and Performance Stock Units (PSUs)
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| Unreleased restricted stock | ||||||
| Unreleased restricted stock at January 31, 2012 | 5,020,800 | |||||
| Granted | 4,077,100 | |||||
| Released | (2,146,100) | |||||
| Canceled | (422,000) | |||||
| Performance adjustment | (14,200) | [1] | ||||
| Unreleased restricted stock at January 31, 2013 | 6,515,600 | 5,020,800 | ||||
| Weighted average grant date fair value | ||||||
| Unreleased restricted stock at January 31, 2012 | $ 33.89 | |||||
| Granted | $ 42.37 | $ 33.32 | $ 37.07 | |||
| Released | $ 34.37 | |||||
| Forfeited | $ 35.58 | |||||
| Performance adjustment | $ 35.95 | [1] | ||||
| Unreleased restricted stock at January 31, 2013 | $ 39.15 | $ 33.89 | ||||
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Performance Stock Units (PSUs)
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| Unreleased restricted stock | ||||||
| Granted | 500,000 | |||||
| Unreleased restricted stock at January 31, 2013 | 800,000 | |||||
| Weighted average grant date fair value | ||||||
| Equity instruments other than options, percent of target | 92.30% | |||||
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