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Discontinued Operations - Summary of Business Consideration to Calculation of the Loss on Sale (Details) - USD ($) $ in Thousands |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Apr. 25, 2019 | Mar. 31, 2018 | Dec. 31, 2018 | Dec. 31, 2017
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |
Net loss on sale of business |  | $ 22 | $ (36) | $ 40
Discontinued Operations Disposed of By Sale [Member] | Cell Therapy Business [Member] |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |
Consideration received | $ 7,000 |  |  |
Transaction costs | (1,161) |  |  |
Net cash proceeds | 5,839 |  |  |
Carrying value of business and assets sold | 12,145 |  |  |
Net loss on sale of business | $ 6,306 |  |  |

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