CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities:
Net loss	$ (18,322)	$ (21,860)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation	2,076	2,294
Stock-based compensation	18,031	9,818
Accretion of discount or amortization of premium on short-term investments	468	19
Amortization of debt issuance costs and debt discount	188	1,793
Changes in operating assets and liabilities:
Accounts receivable	(973)	8,281
Inventory	12,265	(2,938)
Prepaid expenses and other assets	(186)	364
Deferred revenue	(6,553)	280
Accounts payable	(3,053)	(1,229)
Accrued compensation and employee related benefits	422	(937)
Operating lease right-of-use assets	1,458	1,331
Operating lease liabilities	(1,834)	(1,659)
Accrued and other liabilities	364	7,252
Restructuring liabilities	630
Net cash provided by operating activities	4,981	2,809
Investing activities:
Purchases of investments	(19,825)	(5,103)
Proceeds from maturities of investments	41,000	31,275
Purchases of property and equipment	(7,858)	(1,237)
Net cash provided by investing activities	13,317	24,935
Financing activities:
Principal payments on finance lease obligations	(2)	(183)
Proceeds from exercise of stock options and employee stock purchase plan	9,243	3,029
Net cash provided by financing activities	9,241	2,846
Net increase in cash and cash equivalents	27,539	30,590
Cash and cash equivalents
Beginning of period	23,636	66,898
End of period	51,175	97,488
Supplemental disclosure of cashflow information:
Cash paid for interest	863	858
Purchases of property and equipment not yet paid	$ 5,069	$ 464