Fair Value Measurements (Details 1) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Apr. 30, 2012
Level 1 [Member]
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Short-term investments	$ 50,166
Prepaid expenses and other	0
Other long-term assets	0
Total assets measured at fair value	50,166
Level 2 [Member]
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Short-term investments	0
Prepaid expenses and other	373
Other long-term assets	0
Total assets measured at fair value	373
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	2,290
Total assets measured at fair value	2,290
Total [Member]
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Short-term investments	50,166
Prepaid expenses and other	373
Other long-term assets	2,290
Total assets measured at fair value	$ 52,829