Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities
Net loss	$ (95,765)	$ (70,275)	$ (5,152)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	6,176	5,535	5,148
Amortization of premium on investment securities	1,445	288
Gain realized on investment securities	(191)
Impairment of assets	2,138	1,557
Inventory excess adjustments	2,110
Stock based compensation	10,601	7,326	5,157
Loss from changes in fair value of warrants	143	1,481	1,664
Provision for doubtful accounts	984	529	349
Non-cash interest accrual	533
(Gain) loss on sales of property and equipment		(2)	11
Amortization of debt discount		28
Gain from change in fair value of long term debt		(964)	(118)
Loss on debt extinguishment		7,313
Changes in operating assets and liabilities
Accounts receivable	(8,518)	(450)	341
Inventory	(431)	2,929	(890)
Prepaid expenses and other current assets	(2,077)	(3,797)	(137)
Restricted cash	150	(273)
Other assets	(2,812)	(1,041)	(24)
Accounts payable	1,256	1,354	(2,430)
Income taxes payable			(15)
Accrued compensation	2,515	2,572	2,994
Other accrued liabilities	7,411	8,026	4,450
Deferred revenue	430	32	(858)
Net cash (used in) provided by operating activities	(73,902)	(37,832)	10,490
Investing Activities
Purchases of investments	(53,522)	(203,290)
Proceeds from sale of investments	59,185
Proceeds from maturity of investments	64,500
Proceeds from sale of property and equipment		463	15
Purchases of property and equipment, net	(23,136)	(7,852)	(9,957)
Net cash (used in) investing activities	47,027	(210,679)	(9,942)
Financing Activities
Proceeds from issuance of common stock, net of issuance costs		180,001	170
Proceeds from exercise of stock options	3,595	1,258
Proceeds from issuance of common stock under employee stock purchase plan	2,589
Proceeds from issuance of preferred stock, net			55,413
Borrowings under credit facility	8,000
Repayment under credit facility	(1,000)
Costs paid for loan		(6)
Proceeds from short-term financing		42,000
Proceeds from equipment financing			5,105
Repayments of equipment financing		(5,850)	(2,480)
Repayments of secured financings		(20,000)
Proceeds from collection of officer receivable		192
Payment to lender for debt extinguishment		(7,313)
Change in restricted cash			(415)
Deferred offering costs			(1,661)
Net cash provided by financing activities	13,184	190,282	56,132
Net (decrease) increase in cash	(13,691)	(58,229)	56,680
Cash at beginning of period	28,947	87,176	30,496
Cash at end of period	15,256	28,947	87,176
Supplemental disclosure of cash flow information:
Cash paid for interest		2,060	2,063
Purchases of property and equipment through accounts payable and accruals	$ 5,204	765	$ 3,223
Conversion of convertible preferred stock to common stock		$ 240,585