Supplemental Balance Sheet Information - Prepaid expenses and other current assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Supplemental Balance Sheet Information [Abstract]
Prepaid clinical, contract research and manufacturing costs	$ 1,219	$ 481
Interest receivable	398	236
Prepaid insurance	369	533
Other	920	705
Prepaid expenses and other current assets	$ 2,906	$ 1,955

Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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Amount of asset related to consideration paid in advance for other costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

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Amount of asset related to consideration paid in advance for insurance that provides economic benefits within a future period of one year or the normal operating cycle, if longer.

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Supplemental Balance Sheet Information [Abstract]

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