Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Operating Activities
Net loss	$ (28,358)	$ (15,425)
Adjustments to reconcile net loss to net cash and cash equivalents used inoperating activities:
Depreciation and amortization	1,483	1,713
Amortization of debt issuance costs	103	39
Remeasurement of fair value of preferred stock warrant liability	1,800	0
Accretion/amortization of bond discount/premium	52	144
Stock-based compensation	941	343
Loss on disposal of property and equipment	31	48
Impairment loss on property and equipment	450	0
Changes in operating assets and liabilities:
Accounts receivable	402	(226)
Interest receivable	(52)	(16)
Inventory	731	(143)
Other current and long term assets	(328)	(108)
Restricted cash	0	125
Accounts payable	641	(139)
Accrued expenses	868	(484)
Net cash and cash equivalents used in operating activities	(21,236)	(14,148)
Investing Activities
Purchase of investments	(6,240)	(8,150)
Proceeds from sale and maturities of investments	904	7,098
Cash received in acquisition of a business, net of cash paid	246	0
Purchase of property and equipment	(1,377)	(184)
Proceeds from sale of property and equipment	0	49
Net cash and cash equivalents used in investing activities	(6,467)	(1,187)
Financing Activities
Proceeds from issuance of debt	1,998	10,000
Payment of debt	(1,519)	0
Proceeds from issuance of preferred stock, net of issuance costs	28,199	268
Debt issuance costs	0	(44)
Proceeds from exercise of stock options and warrants	143	3
Net cash and cash equivalents provided by financing activities	28,821	10,227
Net increase (decrease) in cash and cash equivalents	1,118	(5,108)
Cash and Cash Equivalents, beginning of year	8,896	14,004
Cash and Cash Equivalents, end of year	10,014	8,896
Supplemental Disclosure for Cash Flow Information
Interest paid	824	306
Supplemental Schedule of Noncash Investing and Financing Activities
Issuance of preferred stock warrants and debt issuance costs	0	128
Conversion of bridge notes to preferred stock	1,998	0
Conversion of preferred stock warrants to common stock warrants	1,909	0
Conversion of preferred stock to common stock	$ 30,197	$ 0