Business Combinations (Details Textual) (USD $)	3 Months Ended			9 Months Ended			3 Months Ended			9 Months Ended		12 Months Ended		9 Months Ended
	Jul. 31, 2011	Oct. 31, 2010	Jul. 31, 2010	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2011 Nortel [Member] MEN Business [Member]	Jan. 31, 2011 MEN Business [Member]	Oct. 31, 2010 MEN Business [Member]	Jul. 31, 2010 MEN Business [Member]	Jul. 31, 2011 MEN Business [Member]	Jul. 31, 2010 MEN Business [Member]	Oct. 31, 2010 MEN Business [Member]	Mar. 19, 2010 MEN Business [Member]	Jul. 31, 2011 MEN Business [Member] Developed Technology Rights [Member]	Jul. 31, 2011 MEN Business [Member] Customer Relationships [Member]	Jul. 31, 2011 MEN Business [Member] Other Intangible Assets [Member]	Jul. 31, 2011 MEN Business [Member] Trade Names [Member]
Business Combinations (Textuals) [Abstract]
Initial purchase price agreement													$ 773,800,000
Aggregate purchase price subsequently adjusted downward upon net working capital transferred to Ciena at closing										80,600,000
Initial cash paid for purchase of business													693,200,000
Period of lease term in connection with the acquisition related to Nortel to lease "Lab 10" building						10 years
Payment received on early termination of lease				33,500,000		33,500,000	33,500,000
Final purchase price										676,800,000
Shortening period of lease term in connection with early termination rights under the lease as directed by governmental authorities										from ten years to five years
Gain recorded				3,289,000			3,300,000	13,800,000
Fair value for contingent consideration right								30,200,000				30,200,000	16,400,000
Transaction, consulting and third party service fees	4,822,000		17,033,000	39,748,000	83,285,000							101,400,000
Restructuring costs	504,000		2,157,000	5,190,000	3,985,000					5,900,000		8,500,000
Additional related to purchases of capitalized information technology equipment	10,200,000			10,200,000				12,400,000				12,400,000
Estimated useful lives on straight line basis, Minimum				0.75										2	0.75	0.75
Estimated useful lives on straight line basis, Maximum				7										7	7	7
Contract intangible asset related to acquired projects in-process										14,600,000
Contract intangible assets billed										13,800,000
Contract intangible assets unbilled										800,000
Expected useful life in months																	9
Specific Revenue on acquisition date									$ 393,843,000		$ 1,174,719,000
In-process research and development amortization period		7 years