Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	May 31, 2012
Cash flows from operating activities:
Net loss	$ (40,048)	$ (16,989)
Adjustments to reconcile net loss to net cash used in operating activities:
Employee stock-based compensation expense	3,594	2,303
Consultant stock-based compensation expense	3	46
Fair value adjustment of common stock warrants	5,981	877
Amortization of intangible assets	86	73
Depreciation of fixed assets	78	27
Realized gain on sale of fixed assets	(12)	0
Gain (loss) on short-term investments	129	(176)
Amortization of debt issuance costs	151	0
Changes in assets and liabilities:
Accounts receivable, net	(26)	0
ATM receivable, net	(5,250)	0
Inventories	(225)	0
Prepaid expenses and other	(1,196)	(2,116)
Intangible assets	(750)	0
Deposits	(115)	0
Accounts payable	(2,284)	(353)
Accrued liabilities	3,944	1,348
Deferred rent	(6)	(1)
Net cash used in operating activities	(35,946)	(14,961)
Cash flows from investing activities:
Purchase of fixed assets	(548)	(259)
Sale of fixed assets	27	0
Change in restricted cash	(50)	(56)
Purchase of short-term investments	(147)	(188)
Sale of short-term investments	22,114	5,000
Net cash provided by investing activities	21,396	4,497
Cash flows from financing activities:
Proceeds from the sale of common stock under an ATM sales agreement	22,367	340
Proceeds from the exercise of common stock warrants	6,706	3,057
Proceeds from the exercise of common stock options	7	227
Note payable	25,000	0
Debt issuance costs	(1,257)	0
Offering costs	89	(120)
Payments on capital lease	(18)	(2)
Net cash provided by financing activities	52,894	3,502
Effect of exchange rates on cash and cash equivalents	(89)	(9)
Net increase (decrease) in cash and cash equivalents	38,255	(6,971)
Cash and cash equivalents, beginning of period	36,313	24,732
Cash and cash equivalents, end of period	74,568	17,761
Supplemental cash flow information:
Interest paid	1,647	0
Supplemental disclosure of non-cash financing activities:
Fair value of warrant liability reclassified to equity upon exercise	8,918	7,107
Acquisition of equipment in exchange for capital lease	$ 68	$ 13