Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities:
Net loss	$ (16,802)	$ (22,278)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,550	1,005
Stock issued for supplemental stock issuance agreement	0	5,154
Warrant revaluation and other finance income	(4,240)	(1,135)
Depreciation and amortization	554	673
Provision for doubtful accounts	(5)	15
Change in operating assets and liabilities:
Accounts receivable	9	11
Inventory	5	(13)
Prepaid expenses and other current assets	812	722
Other assets	0	214
Accounts payable	1,469	(1,904)
Accrued expenses and deferred rent	111	1,693
Deferred revenue	57	331
Net cash used in operating activities	(16,480)	(15,512)
Cash flows from investing activities:
Purchase of property and equipment	(208)	(307)
Net cash used in investing activities	(208)	(307)
Cash flows from financing activities:
Proceeds from common stock offering, net	15,872	0
Proceeds from the exercise of stock options	255	0
Principle payments on capital lease obligations	(3)	0
Net cash provided by financing activities	16,124	0
Effect of exchange rate changes on cash balances	0	1
Net decrease in cash and cash equivalents	(564)	(15,818)
Cash and cash equivalents, beginning of period	37,495	60,033
Cash and cash equivalents, end of period	36,931	44,215
Supplemental Cash Flow Disclosures:
Property and equipment in accounts payable	31	0
Reduction of warrant liability upon issuance of shares	$ 82	$ 0