Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64836518&loc=d3e30700-110894

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=64836518&loc=d3e30690-110894

Name:	us-gaap_ForeignCurrencyTransactionGainLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The Company and Summary of Significant Accounting Policies - Foreign exchange gain (loss) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 subsidiary entity	Dec. 31, 2017 subsidiary company	Dec. 31, 2017 subsidiary	Dec. 31, 2017 USD ($) subsidiary	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
The Company and Summary of Significant Accounting Policies
Equity method investments	7	7
Number of consolidated subsidiaries \| subsidiary	3	3	3	3
Percentage of pure gallium products produces by joint ventures (in hundredths)			99.99%
Foreign Currency Translation [Abstract]
Foreign exchange transaction exchange gains (losses) \| $				$ (602)	$ 232	$ 717