Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net loss	$ (11,798)	$ (16,802)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,616	1,550
Warrant liability revaluation income	(10,518)	(4,240)
Derivative liability revaluation expense	251	0
Depreciation and amortization of long-lived assets	476	554
Recovery of doubtful accounts	(12)	(5)
Intangible asset impairment	3,905	0
Loss on disposal or impairment of property and equipment	64	0
Decrease (increase) in operating assets:
Accounts receivable	12	9
Inventory	482	5
Prepaid expenses and other current assets	1,045	812
Other assets	(64)	0
Increase (decrease) in operating liabilities:
Accounts payable	(212)	898
Related party payable	(10,379)	434
Accrued expenses and deferred rent	(53)	248
Interest payable	46	0
Deferred revenue	(457)	57
Net cash used in operating activities	(25,596)	(16,480)
Cash flows from investing activities:
Purchase of property and equipment	(187)	(208)
Proceeds from the sale of property and equipment	1	0
Net cash used in investing activities	(186)	(208)
Cash flows from financing activities:
Proceeds from private placement offering, net	17,933	0
Proceeds from common stock offering, net	0	15,872
Payment of deferred offering costs	(134)	0
Proceeds from the exercise of stock options	0	255
Principle payments on capital lease obligations	(2)	(3)
Net cash provided by financing activities	17,797	16,124
Net decrease in cash and cash equivalents	(7,985)	(564)
Cash and cash equivalents, beginning of period	29,268	37,495
Cash and cash equivalents, end of period	21,283	36,931
Supplemental Cash Flow Disclosures:
Property and equipment in accounts payable	33	31
Deferred offering costs in accounts payable	41	0
Reduction of warrant liability upon issuance of shares	$ 0	$ 82