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
Realized loss on short-term investments	129		0
Unrealized gain on short-term investments	0		(176)
Amortization of debt issuance costs	151		0
Amortization of deferred offering costs	196		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	(35,750)		(14,961)
Cash flows from investing activities:
Purchase of fixed assets	(616)		(272)
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	21,328		4,484
Cash flows from financing activities:
Proceeds from the sale of common stock under an ATM sales agreement	23,261		352
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
Fundraising costs	(894)		(12)
Debt issuance costs	(1,257)		0
Deferred offering costs	(107)		(120)
Capital lease, net	50		11
Net cash provided by financing activities	52,766		3,515
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	[1]	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

[1] Derived from the Company's audited consolidated financial statements as of December 31, 2012.