Marketable securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Marketable securities
Amortized Cost	$ 53,778	$ 10,505
Gross Unrealized Gains	28
Gross Unrealized Losses		(8)
Marketable securities	53,806	10,497
Commercial paper
Marketable securities
Amortized Cost	14,871
Marketable securities	14,871
Corporate bonds
Marketable securities
Amortized Cost	11,984
Gross Unrealized Gains	26
Marketable securities	12,010
U.S. Treasuries
Marketable securities
Amortized Cost	26,923	10,505
Gross Unrealized Gains	2
Gross Unrealized Losses		(8)
Marketable securities	$ 26,925	$ 10,497

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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