Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net loss	$ (2,709)	$ (14,399)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	1,090	1,047
Depreciation and amortization	46	50
Accretion on marketable securities	172	172
Changes in operating assets and liabilities:
Prepaid and other current assets	(174)	(30)
Other assets	387	272
Accounts payable, accrued liabilities and other liabilities	(2,068)	(1,774)
Net cash used in operating activities	(3,256)	(14,662)
Cash flows from investing activities:
Purchase of marketable securities	(21,819)	(32,312)
Sale of marketable securities	13,646	48,441
Purchase of property and equipment	(14)	0
Net cash provided by (used in) investing activities	(8,187)	16,129
Cash flows from financing activities:
Tax withholding payments on net share settlement equity awards	(148)	(130)
Net proceeds from issuance of common stock	18,715	1,038
Net cash provided by financing activities	18,567	908
Net increase in cash and cash equivalents	7,124	2,375
Cash and cash equivalents at beginning of period	14,032	10,299
Cash and cash equivalents at end of period	$ 21,156	$ 12,674