Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net loss	$ (92,633)	$ (130,041)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization of fixed assets	10,507	8,237
Loss on disposal of property and equipment	301	101
Deferred tax benefit	(231)
Stock-based compensation	23,002	16,773
Amortization of other liabilities	(1,199)	(713)
Amortization of deferred financing costs	40	40
Amortization of premium on short-term investments	56	412
Amortization of intangible assets	645	150
Changes in assets and liabilities, net effects of acquisition:
Accounts receivable, net	(15,663)	(2,930)
Inventory, net	(11,231)	(989)
Prepaid expenses and other current assets	(1,391)	1,702
Accounts payable	8,022	(973)
Accrued liabilities	9,306	5,453
Other short-term liabilities	(29)
Lease incentive obligation	(462)	(159)
Net cash used in operating activities	(70,960)	(102,937)
Cash flows from investing activities:
Purchases of marketable securities	(345,039)	(151,456)
Maturities of marketable securities	195,485	142,813
Purchases of property and equipment	(24,442)	(12,166)
Business acquisition, net of cash acquired	(2,996)
Internally developed software	(25)
Purchased intangible assets	(8,442)
Net cash used in investing activities	(185,459)	(20,809)
Cash flows from financing activities:
Proceeds from exercise of common stock options	3,350	1,049
Proceeds from sale of common stock, net of issuance costs	253,389	144,247
Payments on mortgage payable	(130)	(124)
Proceeds in connection with the Company's employee stock purchase plan	1,629	1,048
Net cash provided by financing activities	258,238	146,220
Effects of exchange rate changes on cash and cash equivalents	97	(164)
Net increase in cash and cash equivalents	1,916	22,310
Cash and cash equivalents, beginning of period	48,921	41,135
Cash and cash equivalents, end of period	50,837	63,445
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment acquired but not paid	3,930	549
Unrealized gain on available-for-sale investments	7	410
Issuance of 158,717 and 341,507 shares of common stock to fund the Company's 401(k) matching contribution for 2016 and 2015, respectively	3,008	2,151
Interest paid	$ 151	$ 157