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Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Revenue from External Customer [Line Items] |  |  |  |
Revenue | $ 16,396 | $ 15,913 | $ 49,318 | $ 51,033
Bill and Hold Arrangement |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Revenue |  |  | $ 7,600 |
Minimum |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Amortization period of capitalized contract costs | 1 year |  | 1 year |

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