Fair Value Measurement (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets:
Short-term investments	$ 77,173	$ 69,899
Foreign currency forward exchange contracts accounted for using hedge accounting		26
Foreign currency forward exchange contracts not accounted for using hedge accounting		119
Total Assets		70,044
Liabilities:
Foreign currency forward exchange contracts accounted for using hedge accounting	34
Foreign currency forward exchange contracts not accounted for using hedge accounting	79
Interest rate swap	243	529
Total Liabilities	356
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Short-term investments
Foreign currency forward exchange contracts not accounted for using hedge accounting
Total Assets
Liabilities:
Foreign currency forward exchange contracts accounted for using hedge accounting
Interest rate swap
Total Liabilities
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Short-term investments	77,173	69,899
Foreign currency forward exchange contracts accounted for using hedge accounting		26
Foreign currency forward exchange contracts not accounted for using hedge accounting		119
Total Assets		70,044
Liabilities:
Foreign currency forward exchange contracts accounted for using hedge accounting	34
Foreign currency forward exchange contracts not accounted for using hedge accounting	79
Interest rate swap	243	529
Total Liabilities	356
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Short-term investments
Foreign currency forward exchange contracts not accounted for using hedge accounting
Total Assets
Liabilities:
Foreign currency forward exchange contracts accounted for using hedge accounting
Interest rate swap
Total Liabilities

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value as of the balance sheet date of all foreign currency derivative assets not designated as hedging instruments.

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Fair value as of the balance sheet date of all foreign currency derivative liabilities not designated as hedging instruments.

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Fair value as of the balance sheet date of all derivative assets designated as foreign currency fair value hedging instruments.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.

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