Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 61,232	$ 33,774	$ 7,042
Marketable securities	15,111	57,699	100,986
Prepaid expenses	1,237	1,707	1,491
Other current assets	1	73	15
Total current assets	77,581	93,253	109,534
Restricted cash	245	245	84
Property and equipment, net	380	414	321
Total assets	78,206	93,912	109,939
Current liabilities:
Accounts payable	1,210	6,716	2,989
Accrued liabilities	1,355	5,483	2,727
Total current liabilities	2,565	12,199	5,716
Other liabilities	24	15	19
Total liabilities	2,589	12,214	5,735
Commitments and contingencies
Stockholders' equity:
Preferred stock
Common stock	4	4	3
Additional paid-in capital	236,751	235,777	175,635
Accumulated deficit	(161,170)	(154,132)	(71,393)
Accumulated other comprehensive income	32	49	(41)
Total stockholders' equity	75,617	81,698	104,204
Total liabilities and stockholders' equity	$ 78,206	$ 93,912	$ 109,939

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Name:	us-gaap_AccountsPayableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).