Certain Balance Sheet Components (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Property, plant and equipment	$ 255,907	$ 250,913
Less: accumulated depreciation	(181,236)	(178,093)
Total property, plant and equipment, net	$ 74,671	$ 72,820