Industry and Geographic Information - Sales to Individual Customers in Excess of 10% of Total Revenue (Detail) (Sales [Member], Customer Concentration Risk [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue, Major Customer [Line Items]
Sales percentage	48.00%	43.00%	42.00%
Customer A [Member]
Revenue, Major Customer [Line Items]
Sales percentage	18.00%	16.00%	16.00%
Customer B [Member]
Revenue, Major Customer [Line Items]
Sales percentage	19.00%	19.00%	18.00%
Customer C [Member]
Revenue, Major Customer [Line Items]
Sales percentage	11.00%	8.00%	8.00%