Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flow from operating activities:
Net loss	$ (11,476)	$ (12,635)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	149	197
Provision for excess inventory	766	0
Stock-based compensation and 401(k) Plan employer match	954	612
Fair value adjustment of common stock warrants	(378)	(162)
Amortization of discount on long-term debt	439	59
Changes in:
Inventory	(1,083)	195
Accounts receivable	67	0
Prepaid expenses and other current assets	75	98
Accounts payable	1,145	659
Accrued expenses	(1,059)	814
Deferred revenue	(54)	0
Other assets	0	(111)
Other liabilities	176	39
Net cash used in operating activities	(10,279)	(10,235)
Cash flows from investing activities:
Purchase of property and equipment	(497)	(120)
Net cash used in investing activities	(497)	(120)
Cash flows from financing activities:
Proceeds from issuance of long-term debt, net of expenses	0	9,850
Proceeds from exercise of common stock options	31	1
Proceeds from exercise of common stock warrants	423	0
Repayment of equipment loans	(19)	(18)
Net cash provided by financing activities	435	9,833
Net decrease in cash and cash equivalents	(10,341)	(522)
Cash and cash equivalents - beginning of period	86,283	26,892
Cash and cash equivalents - end of period	75,942	26,370
Supplementary disclosure of cash flows information:
Interest paid	$ 649	$ 116