Stock-Based Compensation - Valuation Assumptions (Details)	6 Months Ended
Jan. 31, 2020	Jan. 31, 2019
Outstanding stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days
Expected stock price volatility	46.10%
Risk-free interest rate	1.70%
Dividend yield	0.00%
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected stock price volatility, minimum	53.60%	44.00%
Expected stock price volatility, maximum	57.60%	61.90%
Risk-free interest rate, minimum	1.50%	2.50%
Risk-free interest rate, maximum	1.70%	2.70%
Dividend yield	0.00%	0.00%
Employee Stock \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 months	6 months
Employee Stock \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	2 years	2 years

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.

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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

+ 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.

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+ 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.

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No definition available.

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- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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