SEGMENTS AND ENTITY WIDE DISCLOSURES (Details 2) $ in Thousands	3 Months Ended		9 Months Ended
	Jul. 31, 2017 USD ($)	Jul. 31, 2016 USD ($)	Jul. 31, 2017 USD ($) region	Jul. 31, 2016 USD ($)	Oct. 31, 2016 USD ($)
Segment Reporting [Abstract]
Number of geographic regions in which entity operates | region			4
Ciena's geographic distribution of revenue
Revenue	$ 728,719	$ 670,550	$ 2,057,238	$ 1,884,382
Ciena's geographic distribution of equipment, furniture and fixtures
Equipment, building, furniture and fixtures, net	314,850		314,850		$ 288,406
North America
Ciena's geographic distribution of revenue
Revenue	465,238	438,013	1,295,539	1,226,222
EMEA
Ciena's geographic distribution of revenue
Revenue	96,068	104,266	293,387	281,163
CALA
Ciena's geographic distribution of revenue
Revenue	51,709	46,606	120,826	148,312
APAC
Ciena's geographic distribution of revenue
Revenue	115,704	81,665	347,486	228,685
Canada
Ciena's geographic distribution of equipment, furniture and fixtures
Equipment, building, furniture and fixtures, net	208,422		208,422		173,885
United States
Ciena's geographic distribution of revenue
Revenue	438,100	$ 410,000	1,200,000	$ 1,100,000
Ciena's geographic distribution of equipment, furniture and fixtures
Equipment, building, furniture and fixtures, net	94,790		94,790		103,018
Other International
Ciena's geographic distribution of equipment, furniture and fixtures
Equipment, building, furniture and fixtures, net	$ 11,638		$ 11,638		$ 11,503