Fair Value Measurement (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Short-term investments:
Transfer of assets from Level 1 to 2	$ 0	$ 0
Transfer of assets from Level 2 to 1	0	0
Transfer of liabilities from Level 1 to 2	0	0
Transfer of liabilities from Level 2 to 1	0	0
Recurring
Short-term investments:
Available-for-sale securities	50	50
Term deposits	175	60
Total Assets	225	110
Level 1 \| Recurring
Short-term investments:
Term deposits	175	60
Total Assets	175	60
Level 2 \| Recurring
Short-term investments:
Available-for-sale securities	50	50
Total Assets	$ 50	$ 50

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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A savings certificate entitling the Entity (that is, bearer) to receive interest at an established maturity date, based upon a fixed interest rate. A certificate of deposit may be issued in any denomination. Certificates of deposit are generally issued by commercial banks and, therefore, insured by the FDIC (up to the prescribed limit). Certificates of deposit generally restrict holders from withdrawing funds on demand without the incurrence of penalties. Generally, only certificates of deposit with original maturities of three months or less qualify as cash equivalents. Original maturity means original maturity to the entity holding the investment. As a related example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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Amount of transfers of liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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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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