Debt - Components of Debt Obligations and Weighted Average Interest Rate (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Short-term debt	$ 0	$ 4,795
Finance lease liability	317
Unaccreted discount and issuance costs	(528)	(602)
Total long-term debt, net of unaccreted discount and issuance costs	48,229	53,351
Current portion of long-term debt	3,048	2,897
Long-term debt, net of current portion	45,181	50,454
Line of Credit \| Wells Fargo Credit Facility
Debt Instrument [Line Items]
Long-term debt, gross	$ 31,662	$ 35,961
Weighted average interest rate	4.33%	4.41%
Line of Credit \| Mitsubishi Bank Loans \| Minimum
Debt Instrument [Line Items]
Weighted average interest rate	1.05%	1.05%
Line of Credit \| Mitsubishi Bank Loans \| Maximum
Debt Instrument [Line Items]
Weighted average interest rate	1.45%	1.45%
Notes Payable to Banks \| Mitsubishi Bank Loans
Debt Instrument [Line Items]
Long-term debt, gross	$ 10,310	$ 11,094
Notes Payable to Banks \| Mitsubishi Bank Loans And Yamanashi Chou Bank Loans
Debt Instrument [Line Items]
Long-term debt, gross	$ 6,468	$ 6,898
Weighted average interest rate	1.10%	1.10%
Notes payable to suppliers \| Loans With Suppliers
Debt Instrument [Line Items]
Short-term debt	$ 0	$ 4,795

Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Current, Net

No definition available.

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

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-Publisher FASB
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
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-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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