CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net loss	$ (62,906,000)	$ (55,868,000)	$ (38,755,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,817,000	1,699,000	1,415,000
Stock-based compensation	8,065,000	6,730,000	5,153,000
Changes in valuation of warrant liability		(3,566,000)	(7,708,000)
Non-cash interest expense	1,017,000	508,000	131,000
Non-cash deferred manufacturing and development expense		434,000
Deferred income taxes	28,000	7,000	26,000
Loss on disposal of fixed assets			3,000
Impairment of long-lived assets	150,000	0	0
Non-cash tax benefit from other unrealized gain on available-for-sale securities		(3,825,000)
Gain on sale of investment in marketable equity securities	(750,000)
Changes in operating assets and liabilities:
Accounts receivable	(1,074,000)	(301,000)	632,000
Inventories	(1,781,000)	3,991,000	3,033,000
Other assets	1,327,000	1,379,000	(1,655,000)
Accounts payable	3,261,000	(3,866,000)	(973,000)
Accrued liabilities	1,330,000	1,359,000	(1,382,000)
Manufacturing and development obligations	(3,568,000)
Deferred product revenue	(445,000)	190,000	269,000
Net cash used in operating activities	(53,529,000)	(51,129,000)	(39,811,000)
Investing activities
Capital expenditures	(563,000)	(722,000)	(2,106,000)
Proceeds from sale of fixed assets			25,000
Purchases of investments	(82,811,000)	(90,407,000)	(25,981,000)
Proceeds from maturities and sale of investments	63,450,000	92,645,000	24,915,000
Net cash (used in) provided by investing activities	(19,924,000)	1,516,000	(3,147,000)
Financing activities
Net proceeds from equity incentives and warrants	3,068,000	12,767,000	11,592,000
Net proceeds from public offering	22,121,000	75,300,000	18,488,000
Proceeds from loans		10,000,000	9,848,000
Repayment of debt	(622,000)	(113,000)	(3,474,000)
Net cash provided by financing activities	24,567,000	97,954,000	36,454,000
Net (decrease) increase in cash, cash equivalents and restricted cash	(48,886,000)	48,341,000	(6,504,000)
Cash, cash equivalents and restricted cash, beginning of year	71,630,000	23,289,000	29,793,000
Cash, cash equivalents and restricted cash, end of year	22,744,000	71,630,000	23,289,000
Supplemental disclosures:
Cash paid for interest	1,366,000	1,087,000	563,000
Cash paid for income taxes	$ 157,000	153,000	$ 177,000
Unpaid manufacturing and development obligation		$ 7,051,000