Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Operating Activities
Net loss	$ (18,066)	$ (9,062)
Adjustments to reconcile net loss to net cash and cash equivalents used in operating activities:
Depreciation and amortization	594	697
Amortization of debt issuance costs	44	53
Stock-based compensation	1,202	130
Loss on disposal of property and equipment	19	32
Changes in operating assets and liabilities:
Accounts receivable	92	392
Interest receivable	66	16
Inventory	263	(82)
Other current and long term assets	(13)	(5)
Restricted cash	125
Accounts payable	1,812	159
Accrued expenses	500	227
Net cash and cash equivalents used in operating activities	(13,362)	(7,443)
Investing Activities
Proceeds from sale and maturities of investments	6,191	907
Purchase of property and equipment	(910)	(150)
Net cash and cash equivalents provided by investing activities	5,281	757
Financing Activities
Payment of debt	(1,897)
Proceeds from the issuance of common stock, net of issuance costs	52,506
Proceeds from exercise of stock options and warrants	24
Net cash and cash equivalents provided by financing activities	50,633
Net increase (decrease) in cash and cash equivalents	42,552	(6,686)
Cash and Cash Equivalents, beginning of period	10,014	8,896
Cash and Cash Equivalents, end of period	52,566	2,210
Supplemental Disclosure for Cash Flow Information
Interest paid	$ 337	$ 437