Significant Customers - Additional Information (Detail) - Customer	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Revenue, Major Customer [Line Items]
Number of significant customer	2	3	2	2
Number of other customers accounted for more than 10% of revenue	0		0
Trade receivables	10.00%		10.00%
Accounts receivable	51.00%		51.00%		50.00%
Customer One [Member] | Customer Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Revenue	30.00%	22.00%	18.00%	23.00%
Customer Two [Member] | Customer Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Revenue	13.00%	18.00%	15.00%	12.00%
Customer Three [Member] | Customer Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Revenue		13.00%
All Other Customers [Member] | Customer Concentration Risk [Member] | Maximum [Member]
Revenue, Major Customer [Line Items]
Revenue			10.00%	10.00%