Cash and Cash Equivalents and Restricted Cash (Details) $ in Thousands, ¥ in Millions		12 Months Ended
	Feb. 10, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 29, 2016 CNY (¥)	Sep. 04, 2015 USD ($)	Dec. 31, 2014 USD ($)
Cash and Cash Equivalents [Line Items]
Total cash and cash equivalents		$ 62,438	$ 50,611	$ 52,966			$ 112,521
Restricted Cash and Investments [Abstract]
Increase in restricted cash		0	(4,797)	$ 0
Long-term restricted cash		0	4,600
Guangzhou Factory | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Restricted Cash and Investments [Abstract]
Long-term restricted cash		4,900			¥ 32
Surety Bond
Restricted Cash and Investments [Abstract]
Restricted cash						$ 4,600
Increase in restricted cash	$ 4,600
United States
Cash and Cash Equivalents [Line Items]
Total cash and cash equivalents		10,489	3,277
People's Republic of China (PRC)
Cash and Cash Equivalents [Line Items]
Total cash and cash equivalents		23,283	22,142
Asia (excluding the PRC)
Cash and Cash Equivalents [Line Items]
Total cash and cash equivalents		1,405	5,260
Europe
Cash and Cash Equivalents [Line Items]
Total cash and cash equivalents		18,071	19,630
South America
Cash and Cash Equivalents [Line Items]
Total cash and cash equivalents		$ 9,190	$ 302