Fair Value Measurements (Details 1) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands	Jul. 31, 2011
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Prepaid expenses and other	$ 137
Long-term investment	50,227
Other long-term assets	7,600
Total assets measured at fair value	57,964
Level 1 [Member]
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Prepaid expenses and other	0
Long-term investment	50,227
Other long-term assets	0
Total assets measured at fair value	50,227
Level 2 [Member]
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Prepaid expenses and other	137
Long-term investment	0
Other long-term assets	0
Total assets measured at fair value	137
Level 3 [Member]
Assets are presented on Ciena's Condensed Consolidated Balance Sheet
Prepaid expenses and other	0
Long-term investment	0
Other long-term assets	7,600
Total assets measured at fair value	$ 7,600