The Company and Summary of Significant Accounting Policies - Foreign exchange gain (loss) (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) subsidiary company item	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($) item
Schedule of Equity Method Investments [Line Items]
Equity method investments | company	7
Number of consolidated subsidiaries | subsidiary	3
Percentage of pure gallium products produces by joint ventures (in hundredths)	99.99%
Foreign Currency Translation [Abstract]
Foreign exchange transaction exchange gains (losses) | $	$ 232,000	$ 717,000	$ (999,000)
Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Number of consolidated subsidiaries | item	3	3	3