Debt - Components of Debt, Obligations, Weighted Average Interest Rate (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total notes payable and short-term borrowing	$ 4,795	$ 35,607
Total long-term debt, net of unaccreted discount and issuance costs	53,351	46,561
Current portion of long-term debt	2,897	6,005
Long-term debt, net of current portion	50,454	40,556
Mitsubishi Bank
Debt Instrument [Line Items]
Long-term debt, gross	11,094	16,924
Long Term Debt Current
Debt Instrument [Line Items]
Unaccreted discount and issuance costs within current portion of long-term debt	(161)	(86)
Long Term Debt Non Current
Debt Instrument [Line Items]
Unaccreted discount and issuance costs within long-term debt, net of current portion	(441)	(295)
Wells Fargo Credit Facility | Line of Credit
Debt Instrument [Line Items]
Long-term debt, gross	$ 35,961	$ 30,018
Interest Rate	4.41%	3.29%
Mitsubishi Bank Loans And Yamanashi Chou Bank Loans | Notes Payable to Banks
Debt Instrument [Line Items]
Long-term debt, gross	$ 6,898
Interest Rate	1.10%
Notes Payable to Banks | Note payable to Shanghai Pudong Development Bank
Debt Instrument [Line Items]
Total notes payable and short-term borrowing	$ 0	$ 17,000
Interest Rate	0.00%	4.10%
Notes Payable to Banks | Note payable to China CITIC Bank
Debt Instrument [Line Items]
Total notes payable and short-term borrowing	$ 0	$ 17,000
Interest Rate	0.00%	4.00%
Notes Payable
Debt Instrument [Line Items]
Total notes payable and short-term borrowing	$ 4,795	$ 1,607
Minimum | Mitsubishi Bank
Debt Instrument [Line Items]
Interest Rate	1.05%	1.05%
Maximum | Mitsubishi Bank
Debt Instrument [Line Items]
Interest Rate	1.45%	1.45%