ACCOUNTS RECEIVABLE	6 Months Ended
ACCOUNTS RECEIVABLE	Apr. 30, 2017
Receivables [Abstract]
ACCOUNTS RECEIVABLE	ACCOUNTS RECEIVABLE As of April 30, 2017, no single customer accounted for greater than 10.0% of Ciena's net accounts receivable. As of October 31, 2016, one customer accounted for 10.4% of Ciena's net accounts receivable. Ciena has not historically experienced a significant amount of bad debt expense. The allowance for doubtful accounts was $4.5 million and $4.0 million as of April 30, 2017 and October 31, 2016, respectively.

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.