Share-Based Compensation Expense - Assumptions for Awards Granted (Details) - Performance Based Awards	12 Months Ended
Oct. 31, 2020	Nov. 02, 2019	Oct. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility of Ciena common stock, which is a weighted average of implied volatility and historical volatility	31.77%	34.10%	34.93%
Historical volatility of Ciena common stock	36.29%	36.80%	38.24%
Historical volatility of S&P Networking Index	18.40%	17.39%	17.14%
Correlation coefficient	0.5891	0.6251	0.6597
Expected life in years	2 years 10 months 13 days	2 years 10 months 13 days	2 years 10 months 20 days
Risk-free interest rate	1.65%	2.62%	1.94%
Expected dividend yield	0.00%	0.00%	0.00%

Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Correlation Coefficient

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Historical S&P Networking Volatility Rate

+ References

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Historical Volatility Rate

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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.

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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.

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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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- 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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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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