SHORT-TERM AND LONG-TERM DEBT (Details 2) - USD ($)
$ in Thousands
Apr. 30, 2017
Jan. 30, 2017
Oct. 31, 2016
Debt Instrument [Line Items]      
Net Carrying Amount $ 393,377   $ 486,303
Carrying value and estimated current fair value of outstanding convertible notes      
Carrying value 725,026 [1]   767,379
Fair value [2] $ 889,323    
0.875% Convertible Senior Notes due June 15, 2017      
Debt Instrument [Line Items]      
Interest rate on convertible notes (as a percent) 0.875%    
Carrying value and estimated current fair value of outstanding convertible notes      
Carrying value $ 185,221 [1]   231,240
Fair value [2] $ 185,085    
3.75% Convertible Senior Notes due October 15, 2018      
Debt Instrument [Line Items]      
Interest rate on convertible notes (as a percent) 3.75%    
Carrying value and estimated current fair value of outstanding convertible notes      
Carrying value $ 348,248 [1]   347,630
Fair value [2] $ 449,313    
4.0% Convertible Senior Notes due December 15, 2020      
Debt Instrument [Line Items]      
Interest rate on convertible notes (as a percent) 4.00%    
Carrying value and estimated current fair value of outstanding convertible notes      
Carrying value $ 191,557 [1]   188,509
Fair value [2] 254,925    
Secured debt | Term Loan Payable due July 15, 2019      
Debt Instrument [Line Items]      
Net Carrying Amount 0   241,359
Secured debt | Term Loan Payable due April 25, 2021      
Debt Instrument [Line Items]      
Net Carrying Amount 0   244,944
Secured debt | Term Loan Payable due Jan 30, 2022      
Debt Instrument [Line Items]      
Principal Balance 399,000 $ 399,500  
Unamortized Discount (2,153) (500)  
Deferred Debt Issuance Costs (3,470) $ (2,900)  
Net Carrying Amount 393,377 [3]   $ 0
Term loan fair value [3],[4] $ 401,494    
[1] Includes unamortized debt discount, accretion of principal and debt issuance costs.
[2] The convertible notes are categorized as Level 2 in the fair value hierarchy. Ciena estimated the fair value of its outstanding convertible notes using a market approach based upon observable inputs, such as current market transactions involving comparable securities.
[3] Includes unamortized debt discount and debt issuance costs.
[4] Ciena's term loan is categorized as Level 2 in the fair value hierarchy. Ciena estimated the fair value of its term loan using a market approach based upon observable inputs, such as current market transactions involving comparable securities.