v3.19.3

Summary of significant accounting policies - Marketable securities (Details) - USD ($) $ in Thousands | Sep. 30, 2019 | Dec. 31, 2018
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Summary of significant accounting policies |  |
Short-term marketable securities | $ 36,594 | $ 0
Unrealized gains, net of tax in accumulated other comprehensive loss | 41 |
Income tax effect related to unrealized gains in accumulated other comprehensive loss | $ 0 |

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