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Stock-Based Compensation - Summary of Assumptions Used to Estimate Fair Value of Stock Options Granted (Detail) | 12 Months Ended
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Jan. 31, 2014 | Jan. 31, 2013 | Jan. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] |  |  |
Risk-free interest rate | 1.33% | 1.93% | 2.57%
Expected volatility | 32.73% | 35.51% | 44.88%
Expected life | 4 years 8 months 12 days | 4 years 6 months 22 days | 4 years 3 months 4 days
Dividend yield | 3.39% |  |

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