CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating activities
Net loss	$ (37,477)	$ (14,201)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	410	582
Stock-based compensation	2,415	1,911
Changes in revaluation of warrant liability	16,803	(86)
Deferred income taxes	20
Non-cash interest expense		15
(Gain)/Loss on disposal of equipment	96	(9)
Changes in operating assets and liabilities:
Accounts receivable	(2,581)	2,146
Inventories	(1,345)	(3,238)
Other assets	154	(2,006)
Accounts payable	(3,110)	1,020
Accrued liabilities	4,448	2,219
Deferred revenue	34	605
Net cash used in operating activities	(20,133)	(11,042)
Investing activities
Purchases of furniture, equipment and leasehold improvements	(440)	(97)
(Purchases) sales of certain other assets	(14)	1
(Purchases) Maturities of investments	(29,162)	287
Net cash provided by (used in) investing activities	(29,616)	191
Financing activities
Net proceeds from equity incentives	595	281
Net proceeds from public offering	50,981	10,823
Proceeds from warrant exercises		17
Proceeds from revolving line of credit	2,008	1,219
Payments on debt and landlord provided leasehold incentives	(6,176)	(325)
Net cash provided by financing activities	47,408	12,015
Net increase in cash and cash equivalents	(2,341)	1,164
Cash and cash equivalents, beginning of period	26,696	25,497
Cash and cash equivalents, end of period	24,355	26,661
Supplemental disclosures:
Cash paid for interest	242	330
Non-cash conversion of preferred stock to common stock		9,496
Non-cash settlement of warranty claim	$ 1,272