Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (6,108)	$ (24,215)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	3,606	2,580
Stock-based compensation expense	9,738	4,593
Provision for doubtful accounts	286	294
Change in fair value of preferred stock warrant liability		2,651
Noncash interest expense		300
Loss from exit of facilities	385
Loss on disposals of property and equipment		51
Changes in operating assets and liabilities:
Accounts receivable	9,383	22,839
Inventories	(6,799)	16,486
Prepaid expenses and other current assets	309	(2,098)
Deferred cost of revenue	2,010	(2,615)
Other noncurrent assets	(1,333)	(2,803)
Accounts payable and accrued liabilities	(19,000)	(6,485)
Other long-term liabilities	(558)	3,558
Deferred revenue	(3,387)	15,077
Net cash provided by (used in) operating activities	(11,468)	30,213
Cash flows from investing activities:
Purchase of property and equipment	(9,013)	(4,586)
Change in deposits		86
Net cash used in investing activities	(9,013)	(4,500)
Cash flows from financing activities:
Proceeds from borrowings, net		24,691
Repayments of borrowings		(15,000)
Proceeds from equity issued under incentive plans, net of repurchases	17,398	203
Net cash provided by financing activities	17,398	9,894
Net Increase (Decrease) In Cash	(3,083)	35,607
Cash and cash equivalents—Beginning of period	177,250	34,562
Cash and cash equivalents—End of period	174,167	70,169
Supplemental disclosures of cash flow information:
Cash paid for interest	1	136
Cash paid for income taxes	349	66
Supplemental disclosures of noncash investing and financing activities:
Unpaid portion of property and equipment purchases	$ 1,043	893
Unpaid initial public offering cost		186
Issuance of convertible preferred stock warrants in connection with debt		$ 2,032