Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (26,273)	$ (33,864)
Adjustments to reconcile net loss to net cash used for operating activities:
Depreciation	258	274
Unrealized (gain) loss on warrant derivative liabilities	(1,522)	2,608
Amortization of deferred loan costs	103	193
Amortization of debt discount	3,920	3,644
Interest expense added to loan principal	9,767	9,269
Interest expense added to lease liability	1,111	964
Loss on debt conversions	175	58
Loss on early extinguishment of debt and debt refinancing		3,501
Compensation charge for stock awards and share options	473	2,304
Changes in operating assets and liabilities:
Accounts receivable	(2)	3
Prepaid expenses and other current assets	3	2,980
Other assets	73	(444)
Accounts payable	(98)	(79)
Accrued liabilities	(181)	(1,877)
Net cash used for operating activities	(12,193)	(10,466)
Cash flows from investing activities:
Additions to long-term deposit	(2,000)
Additions to property, plant and equipment	(1,726)	(1,006)
Net cash used for investing activities	(3,726)	(1,006)
Cash flows from financing activities:
Net proceeds from issuance of common stock	15,503
Net proceeds from issuance of long-term debt		57,253
Principal payments on long-term debt	(56)	(44,923)
Net cash provided by financing activities	15,447	12,330
Net (decrease) increase in cash and cash equivalents and restricted cash	(472)	858
Cash and cash equivalents and restricted cash, beginning of period	13,163	12,305
Cash and cash equivalents and restricted cash, end of period	$ 12,691	$ 13,163