Basis of Presentation and Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Huawei Technologies [Member] | Revenue [Member]
Concentration Risk [Line Items]
Percentage of concentration of credit risk	41.00%	35.00%	40.00%	36.00%
Ciena Corporation [Member] | Revenue [Member]
Concentration Risk [Line Items]
Percentage of concentration of credit risk	26.00%	17.00%	24.00%	15.00%
Alcatel-Lucent SA [Member] | Revenue [Member]
Concentration Risk [Line Items]
Percentage of concentration of credit risk				11.00%
Company Top Ten Customers [Member] | Revenue [Member]
Concentration Risk [Line Items]
Percentage of concentration of credit risk	92.00%	88.00%	91.00%	88.00%
Customer One [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Percentage of concentration of credit risk			44.00%		45.00%
Customer Two [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Percentage of concentration of credit risk			21.00%		10.00%