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Summary of Significant Accounting Policies - Long Term Investments (Details) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Dealflo Limited |  |
Long Term Investments |  |
Equity investment |  | $ 288
Other Assets |  |
Long Term Investments |  |
Long Term Investments | $ 4,072 | $ 4,361

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