v3.19.1

Fair value measurement (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets:
Marketable securities	$ 4,495	$ 0
Recurring basis
Assets:
Money market accounts	59,910	137,723
Marketable securities	41,383
Total assets	101,293	137,723
Liabilities:
Contingent consideration	961	961
Total liabilities	961	961
Recurring basis | Level 1
Assets:
Money market accounts	59,910	137,723
Marketable securities	4,463
Total assets	64,373	137,723
Recurring basis | Level 2
Assets:
Marketable securities	36,920
Total assets	36,920
Recurring basis | Level 3
Liabilities:
Contingent consideration	961	961
Total liabilities	$ 961	$ 961

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of liability recognized arising from contingent consideration in a business combination.

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Fair value of financial and nonfinancial obligations.

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