ACCOUNTS RECEIVABLE	9 Months Ended
ACCOUNTS RECEIVABLE	Jul. 31, 2017
Receivables [Abstract]
ACCOUNTS RECEIVABLE	ACCOUNTS RECEIVABLE As of July 31, 2017, one customer accounted for 10.3% of Ciena's net accounts receivable and as of October 31, 2016, a different 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 $3.6 million and $4.0 million as of July 31, 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.