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Fair Value Measurements - Schedule of fair value on a recurring basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Fair Value, Inputs, Level 1 [Member] |  |  |
Assets: |  |  |
Money market funds | $ 2,454 | $ 481 |
Fair Value, Inputs, Level 2 [Member] |  |  |
Assets: |  |  |
Short-term investments | 86,223 | 0 | [1]
Company-owned life insurance | 11,787 | 10,464 |
Fair Value, Inputs, Level 3 [Member] |  |  |
Liabilities: |  |  |
Contingent consideration | $ 15,069 | $ 20,039 |
[1] | Investments were measured at carrying value as of December 31, 2018. See table below.

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- Definition Fair value of company owned life insurance. + References No definition available. + Details
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