Subsequent Events	9 Months Ended
Jul. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS Stock Repurchase Program From the end of the third quarter of fiscal 2018 through August 31, 2018, Ciena repurchased an additional 472,542 shares of its common stock, for an aggregate purchase price of $12.4 million at an average price of $26.25 per share, inclusive of repurchases pending settlement. As of August 31, 2018, Ciena has repurchased an aggregate of 3,500,660 shares and has an aggregate of $212.8 million of authorized funds remaining under its Stock Repurchase Program. Stock Repurchases Related to Restricted Stock Unit Tax Withholding Historically, Ciena satisfied employee tax withholding obligations due upon the vesting of restricted stock units (RSUs) through directed open market sales to cover the employee tax obligations. Beginning in the fourth quarter of fiscal 2018, Ciena will change this practice to repurchase shares of common stock delivered with respect to such RSUs in settlement of employee tax withholding obligations due upon the vesting of RSUs. The purchase price for the shares of Ciena’s stock repurchased will be reflected as a reduction to stockholders’ equity. Ciena is required to allocate the purchase price of the repurchased shares as a reduction of common stock and additional paid-in capital. Settlement of Conversions of New Notes Ciena has elected to settle any conversion of the New Notes prior to maturity in a combination of cash and shares, with the cash portion not to exceed an aggregate amount of approximately $400 million. Per the settlement provisions of the indenture governing conversion of the New Notes, an amount of $288.7 million (representing the aggregate principal amount) will be paid in cash on October 15, 2018. To the extent Ciena’s shares trade during the relevant settlement period in excess of the $20.17 per share conversion price, Ciena will pay up to approximately $111.3 million of any amounts due in excess of the aggregate principal amount in cash, and any remaining amounts due will be settled in shares. These amounts will be settled during the first quarter of fiscal 2019. DonRiver Acquisition On August 31, 2018, Ciena entered into a definitive agreement to acquire privately-held DonRiver Holdings, LLC, a global software and services company specializing in federated network and service inventory management solutions within the service provider Operational Support Systems (OSS) environment. The transaction is expected to close during Ciena’s fourth quarter of fiscal 2018 and is subject to customary closing conditions.

SUBSEQUENT EVENTS

Stock Repurchase Program

From the end of the third quarter of fiscal 2018 through August 31, 2018, Ciena repurchased an additional 472,542 shares of its common stock, for an aggregate purchase price of $12.4 million at an average price of $26.25 per share, inclusive of repurchases pending settlement. As of August 31, 2018, Ciena has repurchased an aggregate of 3,500,660 shares and has an aggregate of $212.8 million of authorized funds remaining under its Stock Repurchase Program.

Stock Repurchases Related to Restricted Stock Unit Tax Withholding

Historically, Ciena satisfied employee tax withholding obligations due upon the vesting of restricted stock units (RSUs) through directed open market sales to cover the employee tax obligations. Beginning in the fourth quarter of fiscal 2018, Ciena will change this practice to repurchase shares of common stock delivered with respect to such RSUs in settlement of employee tax withholding obligations due upon the vesting of RSUs. The purchase price for the shares of Ciena’s stock repurchased will be reflected as a reduction to stockholders’ equity. Ciena is required to allocate the purchase price of the repurchased shares as a reduction of common stock and additional paid-in capital.

Settlement of Conversions of New Notes

Ciena has elected to settle any conversion of the New Notes prior to maturity in a combination of cash and shares, with the cash portion not to exceed an aggregate amount of approximately $400 million. Per the settlement provisions of the indenture governing conversion of the New Notes, an amount of $288.7 million (representing the aggregate principal amount) will be paid in cash on October 15, 2018. To the extent Ciena’s shares trade during the relevant settlement period in excess of the $20.17 per share conversion price, Ciena will pay up to approximately $111.3 million of any amounts due in excess of the aggregate principal amount in cash, and any remaining amounts due will be settled in shares. These amounts will be settled during the first quarter of fiscal 2019.

DonRiver Acquisition

On August 31, 2018, Ciena entered into a definitive agreement to acquire privately-held DonRiver Holdings, LLC, a global software and services company specializing in federated network and service inventory management solutions within the service provider Operational Support Systems (OSS) environment. The transaction is expected to close during Ciena’s fourth quarter of fiscal 2018 and is subject to customary closing conditions.