Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating Activities
Net loss	$ (35,961)	$ (8,685)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,758	1,194
Stock-based compensation	2,543	2,396
Premium amortization and discount accretion on investment securities	269	364
Inventory excess adjustments	145
Loss on disposal of property and equipment	12
Impairment of assets	576	20
Non-cash interest accrual	184
Gain on investments	40	(84)
Gain from changes in fair value of warrants	(1,042)	(510)
Provision for doubtful accounts	(101)	234
Changes in operating assets and liabilities
Accounts receivable	6,019	(478)
Inventory	(1,954)	1,404
Prepaid expenses and other current assets	(810)	1,410
Restricted cash	317	(79)
Other assets	165	(561)
Accounts payable	(1,902)	1,825
Accrued compensation	(1,739)	347
Other accrued liabilities	5,612	1,603
Deferred revenue	18	71
Deferred rent, net of current portion	1,548
Net cash (used in) provided by operating activities	(24,303)	471
Investing Activities
Purchases of investments	(3,995)	(14,079)
Proceeds from sale of investments	25,053	10,599
Proceeds from maturity of investments	3,000	10,000
Proceeds from sale of property and equipment		225
Purchases of property and equipment, net	(6,338)	(3,484)
Net cash provided by investing activities	17,720	3,261
Financing Activities
Proceeds from exercise of stock options	413	1,306
Net cash provided by financing activities	413	1,306
Net (decrease) increase in cash	(6,170)	5,038
Cash at beginning of period	15,256	28,947
Cash at end of period	$ 9,086	$ 33,985