CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (54,899)	$ (59,296)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,875	2,270
Amortization of investment discount	153	46
Equity-based compensation	19,058	12,291
Amortization of debt discount and issuance costs	9,250	8,256
(Gain) loss on disposal of property and equipment	(202)	546
Contributions to deferred compensation plan	(343)	(248)
Gain on extinguishment of debt	(9,840)	0
(Increase) decrease in assets:
Accounts receivable	(719)	532
Inventory and instruments in property and equipment	(527)	(1,734)
Prepaid expense and other	860	(1,267)
Increase (decrease) in liabilities:
Accounts payable	1,017	76
Accrued liabilities, and other	(436)	(759)
Accrued interest	(1,059)	(1,071)
Deferred revenue and income	93	67
Deferred compensation	343	240
Net cash used in operating activities	(35,376)	(40,051)
Cash flows from investing activities:
Purchases of equipment	(202)	(1,364)
Purchases of marketable securities	(22,345)	(44,589)
Maturities of marketable securities	33,601	41,707
Net cash provided by (used in) investing activities	11,054	(4,246)
Cash flows from financing activities:
Proceeds from issuance of common and preferred stock	22,640	0
Proceeds from exercise of options	1,456	4,458
Proceeds from issuance of common stocks under employee purchase plan	245	296
Proceeds from debt	0	5,552
Payment of debt	(6)	(13)
Net cash provided by financing activities	24,335	10,293
Effect of exchange rate on cash	(69)	19
Decrease in cash and cash equivalents	(56)	(33,985)
Cash and cash equivalents, beginning of period	35,781	61,014
Cash and cash equivalents, end of period	35,725	27,029
Non-cash investing activities:
Net transfer of instruments from inventory to property and equipment	508	1,284
Supplemental cash flow information:
Interest paid	4,288	4,288
Income taxes paid, net of refunds	0	46
Extinguishment of Convertible Senior Notes through issuance of common stock	$ 34,545	$ 0