Marketable securities (Tables)

3 Months Ended

Mar. 31, 2020

Marketable securities

Schedule of reconciliation of marketable securities from cost basis to fair value

			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
March 31, 2020
Commercial paper	$	5,983	$	—	$	—	$	5,983
Corporate bonds		11,997		—		(4)		11,993
	$	17,980	$	—	$	(4)	$	17,976

			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
December 31, 2019
Commercial paper	$	11,940	$	—	$	—	$	11,940
Corporate bonds		11,990		20		—		12,010
U.S. Treasuries		13,484		5		—		13,489
	$	37,414	$	25	$	—	$	37,439