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Business and Summary of Significant Accounting Policies - Assumption Used to Estimate the Fair Value of Stock-Based Awards (Details)
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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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Performance Stock Unit
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| Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items] |
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| Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate |
0.00% |
[1] |
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| Range of expected volatilities |
34.00% |
[1] |
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| Range of risk-free interest rates |
0.10% |
[1] |
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Performance Stock Unit | Minimum
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| Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items] |
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| Expected forfeitures |
7.20% |
[1] |
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Performance Stock Unit | Maximum
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| Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items] |
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| Expected forfeitures |
7.70% |
[1] |
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Employee Qualified Stock Purchase Plan 1998 ESP Plan
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| Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items] |
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| Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate |
0.00% |
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0.00% |
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0.00% |
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Employee Qualified Stock Purchase Plan 1998 ESP Plan | Minimum
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| Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items] |
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| Range of expected volatilities |
27.00% |
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41.00% |
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34.00% |
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| Range of expected lives |
6 months |
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6 months |
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6 months |
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| Range of risk-free interest rates |
0.10% |
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0.10% |
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0.10% |
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| Expected forfeitures |
7.20% |
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7.70% |
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7.80% |
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Employee Qualified Stock Purchase Plan 1998 ESP Plan | Maximum
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| Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items] |
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| Range of expected volatilities |
36.00% |
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44.00% |
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44.00% |
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| Range of expected lives |
2 years |
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2 years |
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2 years |
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| Range of risk-free interest rates |
0.40% |
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0.30% |
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0.80% |
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| Expected forfeitures |
7.70% |
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7.80% |
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10.50% |
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Stock Options Plan
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| Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items] |
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| Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate |
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0.00% |
[2] |
0.00% |
[2] |
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Stock Options Plan | Minimum
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| Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items] |
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| Range of expected volatilities |
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41.00% |
[2] |
40.00% |
[2] |
| Range of expected lives |
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3 years 7 months 6 days |
[2] |
2 years 7 months 6 days |
[2] |
| Range of risk-free interest rates |
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0.50% |
[2] |
0.50% |
[2] |
| Expected forfeitures |
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7.70% |
[2] |
7.80% |
[2] |
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Stock Options Plan | Maximum
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| Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items] |
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| Range of expected volatilities |
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45.00% |
[2] |
49.00% |
[2] |
| Range of expected lives |
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4 years 7 months 6 days |
[2] |
4 years 9 months 18 days |
[2] |
| Range of risk-free interest rates |
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0.80% |
[2] |
1.90% |
[2] |
| Expected forfeitures |
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7.80% |
[2] |
10.50% |
[2] |
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