CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating activities
Net loss	$ (16,863)	$ (9,460)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	476	443
Stock-based compensation	1,776	1,474
Changes in valuation of warrant liability		(6,296)
Non-cash interest expense	300	64
Deferred income taxes	9	1
Non-cash tax expense from other unrealized loss on available-for-sale securities	768
Changes in operating assets and liabilities:
Accounts receivable	1,708	340
Inventories	(488)	(1,220)
Other assets	(213)	(116)
Accounts payable	995	484
Accrued liabilities	(639)	(1,488)
Manufacturing and development obligations	(924)
Deferred revenue	52	23
Net cash used in operating activities	(13,043)	(15,751)
Investing activities
Capital expenditures	(43)	(59)
Purchases of investments	(50,544)	(69,982)
Proceeds from maturities of investments	5,500	4,400
Restricted cash	38	47
Net cash used in investing activities	(45,049)	(65,594)
Financing activities
Net proceeds from the issuance of common stock in connection with equity incentive plans	698	999
Net proceeds from public offering	7,199	75,527
Repayment of debt	(32)	(28)
Net cash provided by financing activities	7,865	76,498
Net decrease in cash and cash equivalents	(50,227)	(4,847)
Cash and cash equivalents, beginning of year	71,018	22,781
Cash and cash equivalents, end of year	$ 20,791	$ 17,934