Document and Entity Information - shares	6 Months Ended
	Apr. 30, 2018	Jun. 04, 2018
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, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		142,827,652