Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net loss	$ (19,065)	$ (6,108)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	5,677	3,606
Stock-based compensation expense	36,535	9,738
Provision for doubtful accounts	53	286
Non-cash interest expense	412
Loss from exit of facilities		385
Amortization of premiums on short-term investments	(265)
Changes in operating assets and liabilities:
Accounts receivable	(21,012)	9,383
Inventories	(3,858)	(6,799)
Prepaid expenses and other current assets	(5,377)	309
Operating lease right-of-use assets	7,738
Deferred cost of revenue	1,144	2,010
Other noncurrent assets	10	(1,333)
Accounts payable and accrued liabilities	32,255	(19,000)
Operating lease liabilities	(4,405)
Other long-term liabilities	(1,197)	(558)
Deferred revenue	(14,611)	(3,387)
Net cash provided by (used in) operating activities	14,034	(11,468)
Cash flows from investing activities:
Purchase of property and equipment	(23,171)	(9,013)
Purchases of short-term investments	(12,365)
Sales/maturities of short-term investments	43,810
Net cash provided by (used in) investing activities	8,274	(9,013)
Cash flows from financing activities:
Proceeds from equity issued under incentive plans	19,145	17,398
Proceeds from equity issued under at-the-market program, net of offering costs	179,360
Net cash provided by financing activities	198,505	17,398
Net Increase (Decrease) in cash, cash equivalents and restricted cash	220,813	(3,083)
Cash, cash equivalents and restricted cash—Beginning of period	155,564	177,250
Cash, cash equivalents and restricted cash—End of period	376,377	174,167
Cash, cash equivalents and restricted cash at end of period:
Cash and cash equivalents	375,509	174,167
Restricted cash	868
Cash, cash equivalents and restricted cash—End of period	376,377	174,167
Supplemental disclosures of cash flow information:
Cash paid for interest	960	1
Cash paid for income taxes	636	349
Supplemental disclosures of non-cash investing and financing activities:
Unpaid portion of property and equipment purchases	6,984	$ 1,043
Unpaid portion of at-the-market offering costs	$ 459