CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net loss	$ (59,296,000)	$ (62,970,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,270,000	1,862,000
Amortization of investment discount	43,000	(400,000)
Equity-based compensation	12,291,000	9,409,000
Amortization of debt discount and issuance costs	8,256,000	7,370,000
Realized loss on sale of investments	3,000	0
Loss on disposal of property and equipment	546,000	577,000
Contributions to deferred compensation plan	(248,000)	0
(Increase) decrease in assets:
Accounts receivable	532,000	(782,000)
Inventory and instruments in property and equipment	(1,734,000)	(3,286,000)
Prepaid expense and other	(1,267,000)	(319,000)
Increase (decrease) in liabilities:
Accounts payable	76,000	788,000
Accrued liabilities, and other	(759,000)	(2,115,000)
Accrued interest	(1,071,000)	(1,071,000)
Deferred revenue and income	67,000	33,000
Deferred compensation	240,000	(25,000)
Net cash used in operating activities	(40,051,000)	(50,929,000)
Cash flows from investing activities:
Purchases of equipment	(1,364,000)	(148,000)
Purchase of marketable securities	(44,589,000)	(20,710,000)
Proceeds from sales of marketable securities	0	13,400,000
Maturities of marketable securities	41,707,000	78,922,000
Net cash (used in) provided by investing activities	(4,246,000)	71,464,000
Cash flows from financing activities:
Proceeds from issuance of common stock	296,000	1,363,000
Proceeds from exercise of options	4,458,000	4,879,000
Proceeds from debt	5,552,000	0
Payment of debt	(13,000)	0
Net cash provided by financing activities	10,293,000	6,242,000
Effect of exchange rate on cash	19,000	(99,000)
(Decrease) increase in cash and cash equivalents	(33,985,000)	26,678,000
Cash and cash equivalents, beginning of period	61,014,000	66,260,000
Cash and cash equivalents, end of period	27,029,000	92,938,000
Non-cash investing activities:
Net transfer of instruments from inventory to property and equipment	1,284,000	3,225,000
Supplemental cash flow information:
Interest paid	4,288,000	4,288,000
Income taxes paid, net of refunds	$ 46,000	$ 54,000