Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating Activities
Net loss	$ (57,858)	$ (47,315)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	4,177	4,363
Amortization of premium on investment securities	1,145
Amortization of debt discount		28
Gain on sales of property and equipment		(2)
Impairment of assets	407	1,258
Non-cash interest accrual	383
Gain on investments	(192)
Stock based compensation	7,965	4,906
(Gain) loss from changes in fair value of warrants	(91)	1,509
Loss from change in fair value of long term debt		312
Provision for doubtful accounts	354	279
Changes in operating assets and liabilities
Accounts receivable	(3,900)	(157)
Inventory	(1,156)	(1,863)
Prepaid expenses and other current assets	(4,057)	(3,668)
Restricted cash	54	(303)
Other assets	(3,028)	(573)
Accounts payable	1,653	102
Accrued compensation	1,662	1,647
Other accrued liabilities	1,552	6,341
Deferred revenue	432	(7)
Deferred rent	6,092
Net cash used in operating activities	(44,406)	(33,143)
Investing Activities
Purchases of investments	(48,519)	(26,353)
Proceeds from sale of investments	59,185
Proceeds from maturity of investments	34,000
Purchases of property and equipment, net	(14,577)	(6,452)
Net cash provided by (used in) investing activities	30,089	(32,805)
Financing Activities
Proceeds from initial public offering, net of issuance costs		180,628
Proceeds from exercise of stock options	2,722
Proceeds from issuance of common stock under employee stock purchase plan	970
Borrowings under credit facility	8,000
Repayment under credit facility	(1,000)
Costs paid for loan		(6)
Repayments of equipment financing		(5,850)
Proceeds from collection of officer receivable		192
Net cash provided by financing activities	10,692	174,964
Net (decrease) increase in cash	(3,625)	109,016
Cash at beginning of period	28,947	87,176
Cash at end of period	$ 25,322	$ 196,192