Document and Entity Information - shares	6 Months Ended
	Apr. 30, 2019	Jun. 07, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	CIENA CORP
Entity Central Index Key	0000936395
Current Fiscal Year End Date	--10-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Apr. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		155,088,524