CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net loss	$ (13,885)	$ (18,598)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	413	469
Stock-based compensation	2,315	2,147
Non-cash interest expense	269	195
Deferred income taxes	1	7
Gain on sale of investment in marketable equity securities		(18)
Changes in operating assets and liabilities:
Accounts receivable	1,926	1,285
Inventories	1,224	(388)
Other assets	(1,475)	(310)
Accounts payable	(122)	198
Accrued liabilities and other non-current liabilities	(1,341)	(1,724)
Manufacturing and development obligations	164	76
Deferred product revenue	186	313
Net cash used in operating activities	(10,325)	(16,348)
Investing activities
Capital expenditures	(52)	(185)
Purchases of investments	(56,941)	(10,158)
Proceeds from maturities and sale of investments	12,250	16,018
Net cash (used in) provided by investing activities	(44,743)	5,675
Financing activities
Net proceeds from equity incentives	1,295	422
Net proceeds from (payments for) public offering	57,564	(30)
Repayment of debt	(32)	(1,271)
Net cash provided by (used in) financing activities	58,827	(879)
Net increase (decrease) in cash, cash equivalents and restricted cash	3,759	(11,552)
Cash, cash equivalents and restricted cash, beginning of period	13,930	22,744
Cash, cash equivalents and restricted cash, end of period	$ 17,689	$ 11,192