Segment Information and Geographic Data - Net Sales to Significant Customers as a Percent of Total Net Sales (Detail) - Sales Revenue, Net - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Customer A
Revenue, Major Customer [Line Items]
Concentration risk percentage	18.30%	20.30%	21.30%
Customer A | AIT
Revenue, Major Customer [Line Items]
Concentration risk percentage	5.30%	6.20%	6.30%
Customer A | EVM
Revenue, Major Customer [Line Items]
Concentration risk percentage	13.00%	14.10%	15.00%
Customer B
Revenue, Major Customer [Line Items]
Concentration risk percentage	13.70%	15.70%	14.20%
Customer B | AIT
Revenue, Major Customer [Line Items]
Concentration risk percentage	4.70%	5.60%	5.30%
Customer B | EVM
Revenue, Major Customer [Line Items]
Concentration risk percentage	9.00%	10.10%	8.90%
Customer C
Revenue, Major Customer [Line Items]
Concentration risk percentage	16.60%	14.10%	13.20%
Customer C | AIT
Revenue, Major Customer [Line Items]
Concentration risk percentage	6.10%	6.20%	6.20%
Customer C | EVM
Revenue, Major Customer [Line Items]
Concentration risk percentage	10.50%	7.90%	7.00%