CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net loss	$ (9,738)	$ (14,055)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	4	10
Stock-based compensation	1,713	2,008
Changes in assets and liabilities:
Prepaid expenses and other assets	36	(80)
Accounts payable and accrued liabilities	(602)	2,552
Accrued payroll and related expenses	31	(1,923)
Accounts receivables	(2)	(2)
Income tax liability	(396)	6
Net cash used in operating activities	(8,954)	(11,484)
Cash flows from investing activities:
Purchase of investments	(3,391)	(924)
Proceeds from sale or maturity of investments	2,423	1,635
Net cash (used in) provided by investing activities	(968)	711
Cash flows from financing activities:
Proceeds from exercise of options	816	0
Proceeds from sale of common stock	5,697	11,639
Payments of taxes on restricted stock units	(47)	(33)
Net cash provided by financing activities	6,466	11,606
Net change in cash and cash equivalents	(3,456)	833
Cash and cash equivalents, beginning of period	7,611	3,135
Cash and cash equivalents, end of period	4,155	3,968
ASC 606 [Member]
Non-cash transactions
Deferred revenue reclassified to retained earnings - ASC 606 adoption	$ 0	$ 2,500