Geographic and Segment Information - Additional Information (Detail) - Segments	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments			2
Customer Concentration Risk [Member] | Net Sales [Member] | Top Ten Customers [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	69.00%	67.00%	68.00%	63.00%
Customer Concentration Risk [Member] | Net Sales [Member] | Top Customer One [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	35.30%	28.90%	32.40%	23.90%
Geographic Concentration Risk [Member] | Net Sales [Member] | Asia Pacific Other Than Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	79.00%		77.60%
Geographic Concentration Risk [Member] | Net Sales [Member] | Taiwan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	18.30%	23.80%	19.10%	24.10%
Geographic Concentration Risk [Member] | Net Sales [Member] | CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage		70.30%		69.10%
Geographic Concentration Risk [Member] | Property, Plant and Equipment [Member] | Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage			98.00%