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Employee Incentive Plans Schedule of Black-Scholes Option Pricing Model Estimated Fair Value Assumptions (Details) | 12 Months Ended
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Jan. 31, 2020 | Jan. 31, 2019 | Jan. 31, 2018
Stock options |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Expected volatility | 43.00% | 40.00% |
Expected volatility, minimum |  |  | 40.00%
Expected volatility, maximum |  |  | 41.00%
Expected term (in years) | 6 years 3 months 18 days | 6 years 3 months 18 days |
Risk-free interest rate |  | 2.70% |
Risk-free interest rate, minimum | 1.55% |  | 1.87%
Risk-free interest rate, maximum | 2.27% |  | 2.21%
Expected dividend yield | 0.00% | 0.00% | 0.00%
Stock options | Minimum |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Expected term (in years) |  |  | 6 years 3 months 18 days
Stock options | Maximum |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Expected term (in years) |  |  | 6 years 4 months 24 days
ESPP |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Expected volatility, minimum | 43.00% | 39.00% | 32.00%
Expected volatility, maximum | 59.00% | 70.00% | 38.00%
Risk-free interest rate, minimum | 1.53% | 2.12% | 0.95%
Risk-free interest rate, maximum | 2.05% | 2.62% | 1.73%
Expected dividend yield | 0.00% | 0.00% | 0.00%
ESPP | Minimum |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Expected term (in years) | 6 months | 6 months | 6 months
ESPP | Maximum |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Expected term (in years) | 1 year | 1 year | 1 year 2 months 12 days

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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References No definition available. + Details
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- Definition The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References No definition available. + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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- Definition The maximum risk-free interest rate assumption that is used in valuing an option on its own shares. + References No definition available. + Details
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- Definition The minimum risk-free interest rate assumption that is used in valuing an option on its own shares. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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