Geographic and Segment Information - Net Sales by Region, Based on Location of Products are Billed (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	$ 152,430	$ 154,382	$ 162,015	$ 164,885	$ 167,652	$ 194,332	$ 172,070	$ 164,164	$ 633,712	$ 698,218	$ 734,177
Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales									241,715	260,139	313,634
Asia Pacific (other than Korea) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales									316,562	324,248	284,429
U.S.A. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales									51,164	91,308	100,790
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales									23,461	21,159	32,136
Others [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales									$ 810	$ 1,364	$ 3,188