Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net loss	$ (15,281)	$ (16,266)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,044	739
Stock issued for supplemental stock issuance agreement	0	5,154
Warrant revaluation and other finance expense (income)	1,061	(958)
Depreciation and amortization	346	452
Provision for doubtful accounts	(1)	16
Change in operating assets and liabilities:
Accounts receivable	2	(2)
Inventory	87	121
Prepaid expenses and other current assets	549	496
Other assets	0	214
Accounts payable	833	(1,590)
Accrued expenses and other long-term liabilities	489	1,206
Deferred revenue	84	132
Net cash used in operating activities	(10,787)	(10,286)
Cash flows from investing activities:
Purchase of property and equipment	(111)	(211)
Net cash used in investing activities	(111)	(211)
Cash flows from financing activities:
Proceeds from the exercise of stock options	255	0
Principle payments on capital lease obligations	(2)	0
Net cash provided by financing activities	253	0
Net decrease in cash and cash equivalents	(10,645)	(10,497)
Cash and cash equivalents, beginning of period	37,495	60,033
Cash and cash equivalents, end of period	$ 26,850	$ 49,536