Industry and Geographic Information - Sales to Individual Customers in Excess of 10% of Total Revenues (Detail) - Sales [Member]	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Revenue, Major Customer [Line Items]
Sales percentage	10.00%
Customer Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Sales percentage	50.00%	42.00%
Customer Concentration Risk [Member] | Customer A [Member]
Revenue, Major Customer [Line Items]
Sales percentage	23.00%	16.00%
Customer Concentration Risk [Member] | Customer B [Member]
Revenue, Major Customer [Line Items]
Sales percentage	16.00%	16.00%
Customer Concentration Risk [Member] | Customer C [Member]
Revenue, Major Customer [Line Items]
Sales percentage	11.00%	10.00%