Debt (Schedule of Debt) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Revolving credit facility	$ 108,500	$ 96,000
Debt:
Total debt	3,311	2,516
Less: current portion	(2,752)	(1,533)
Total long-term debt, net	559	983
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Revolving credit facility	$ 108,500	96,000
Debt:
Debt, maturity	June 2024
Suzhou Short-Term Credit Line [Member]
Debt Instrument [Line Items]
Revolving credit facility	$ 2,099	0
Debt:
Debt, maturity	August 2020
Maximum [Member] \| Revolving Credit Facility [Member]
Debt:
Long-term debt, weighted average interest rate	3.12%
Maximum [Member] \| Suzhou Short-Term Credit Line [Member]
Debt:
Outstanding credit lines interest rate	5.00%
Minimum [Member] \| Revolving Credit Facility [Member]
Debt:
Long-term debt, weighted average interest rate	3.07%
Minimum [Member] \| Suzhou Short-Term Credit Line [Member]
Debt:
Outstanding credit lines interest rate	4.70%
PST Short-Term Obligations [Member]
Debt Instrument [Line Items]
Short-term debt	$ 149	989
Debt:
Debt, maturity	December 2019
Interest rate	6.00%
PST Long-Term Notes [Member]
Debt:
Long-term debt	$ 1,063	$ 1,527
Debt, maturity	November 2021
Interest rate	7.00%

Amount of short-term and long-term debt and lease obligation.

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Fair value of the amount outstanding under the credit facility.

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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.

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