v3.19.2

Summary of significant accounting policies - Marketable securities (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Dec. 31, 2018
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Summary of significant accounting policies |  |
Short-term marketable securities | $ 42,799 | $ 0
Unrealized gains, net of tax in accumulated other comprehensive loss | 45 |
Income tax effect related to unrealized gains in accumulated other comprehensive loss | $ 0 |

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- Definition Amount, after tax, of accumulated unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e681-108580 + Details
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