Fair Value Measurements (Details 1) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Jul. 31, 2012
Level 1 [Member]
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Short-term investments	$ 50,115
Prepaid expenses and other	0
Other long-term assets	0
Total assets measured at fair value	50,115
Level 2 [Member]
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Short-term investments	0
Prepaid expenses and other	34
Other long-term assets	0
Total assets measured at fair value	34
Level 3 [Member]
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Short-term investments	0
Prepaid expenses and other	0
Other long-term assets	3,860
Total assets measured at fair value	3,860
Total [Member]
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Short-term investments	50,115
Prepaid expenses and other	34
Other long-term assets	3,860
Total assets measured at fair value	$ 54,009