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Employee Benefit Plans (Schedule Of Restricted Stock Units Activity) (Details) (USD $)
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12 Months Ended |
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Jan. 31, 2012
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| Employee Benefit Plans [Abstract] | |
| Shares, Outstanding at January 31, 2011 | 543,841 |
| Shares, Granted | 272,949 |
| Shares, Vested | (210,094) |
| Shares, Canceled | (38,198) |
| Shares, Outstanding at January 31, 2012 | 568,498 |
| Weighted-average grant date fair value, Outstanding at January 31, 2011 | $ 38.60 |
| Weighted-average grant date fair value, Granted | $ 48.53 |
| Weighted-average grant date fair value, Vested | $ 37.40 |
| Weighted-average grant date fair value, Canceled | $ 41.35 |
| Weighted-average grant date fair value, Outstanding at January 31, 2012 | $ 43.74 |