RESTRUCTURING COSTS (Details) $ in Thousands		3 Months Ended		6 Months Ended
		Apr. 30, 2016 USD ($)	Apr. 30, 2015 USD ($)	Apr. 30, 2016 USD ($)	Apr. 30, 2015 USD ($) employee
Activity and balance of the restructuring liability accounts
Balance at beginning of period				$ 1,279	$ 1,315
Additional liability recorded				929
Restructuring costs		$ 535	$ (17)	919	8,068
Adjustments to previous estimates				(10)
Cash payments				(1,026)	(7,778)
Balance at end of period		1,172	1,605	1,172	1,605
Current restructuring liabilities		1,006	1,122	1,006	1,122
Non-current restructuring liabilities		166	483	166	483
Workforce reduction
Activity and balance of the restructuring liability accounts
Balance at beginning of period				591	181
Additional liability recorded				929
Restructuring costs	[1]				8,068
Adjustments to previous estimates				0
Cash payments				(823)	(7,518)
Balance at end of period		697	731	697	731
Current restructuring liabilities		697	731	697	731
Non-current restructuring liabilities		0	0	0	$ 0
Workforce deduction | employee					125
Consolidation of excess facilities
Activity and balance of the restructuring liability accounts
Balance at beginning of period				688	$ 1,134
Additional liability recorded				0
Restructuring costs					0
Adjustments to previous estimates				(10)
Cash payments				(203)	(260)
Balance at end of period		475	874	475	874
Current restructuring liabilities		309	391	309	391
Non-current restructuring liabilities		$ 166	$ 483	$ 166	$ 483

[1] During the fiscal quarter ended January 31, 2015, Ciena recorded a charge of $8.1 million of severance and other employee-related costs associated with a global workforce reduction of approximately 125 employees.