Segments, Concentrations and Geographic Information - Net Sales to Third Parties by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 237,323	$ 223,357	$ 477,708	$ 438,792
North America (primarily U.S.) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	119,023	115,236	244,716	230,376
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	91,308	84,983	184,790	168,275
Asia And Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 26,992	$ 23,138	$ 48,202	$ 40,141