Segment Information - Net Sales by Market (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net sales	$ 197,563	$ 287,728	$ 264,860
United States
Segment Reporting Information [Line Items]
Net sales	3,348	4,100	3,246
Canada
Segment Reporting Information [Line Items]
Net sales	1,938	1,809	2,746
PERU
Segment Reporting Information [Line Items]
Net sales	508	0	0
Hong Kong
Segment Reporting Information [Line Items]
Net sales	174,926	263,482	245,737
China
Segment Reporting Information [Line Items]
Net sales	7,282	9,086	4,425
Taiwan
Segment Reporting Information [Line Items]
Net sales	5,591	6,213	5,965
South Korea
Segment Reporting Information [Line Items]
Net sales	466	691	1,129
Commonwealth of Independent States (Russia, Kazakhstan and Ukraine)
Segment Reporting Information [Line Items]
Net sales	913	858	1,139
Europe [Member]
Segment Reporting Information [Line Items]
Net sales	2,278	1,234	382
Other foreign countries
Segment Reporting Information [Line Items]
Net sales	$ 313	$ 255	$ 91