Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net loss	$ (59,237,000)	$ (53,020,000)	$ (64,790,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	16,101,000	14,451,000	11,393,000
Amortization of developed technology	11,918,000	11,910,000	11,200,000
Depreciation and amortization	3,653,000	4,014,000	4,605,000
Provision for excess and obsolete inventory	2,293,000	1,614,000	1,807,000
Lease amortization	497,000	2,017,000	(516,000)
Amortization of debt discounts, premiums and issuance costs	624,000	545,000	1,936,000
Impairment of intangible asset	0	0	443,000
Loss from extinguishment of debt	9,000	0	12,020,000
Loss on disposal of property and equipment	12,000	212,000	89,000
Other non-cash items	2,000	426,000	200,000
Changes in assets and liabilities:
Accounts receivable, net	6,729,000	(7,628,000)	(2,075,000)
Inventories, net	(4,782,000)	(8,636,000)	(3,047,000)
Prepaid expenses and other assets	(436,000)	(877,000)	(1,400,000)
Accounts payable	1,281,000	3,356,000	787,000
Accrued compensation and related benefits	(8,721,000)	8,627,000	(9,310,000)
Deferred revenue	(3,208,000)	2,111,000	2,129,000
Other liabilities	(10,796,000)	5,461,000	(681,000)
Net cash used in operating activities	(44,061,000)	(15,417,000)	(35,210,000)
Investing activities
Proceeds from NIH Contract	1,318,000	21,036,000	0
Acquisition, net of cash acquired	0	(5,154,000)	0
Purchases of investments	0	0	(62,370,000)
Proceeds from sale of investments	0	5,010,000	0
Proceeds from maturities of investments	0	31,800,000	25,600,000
Purchases of property and equipment, net	(13,264,000)	(12,717,000)	(2,531,000)
Net cash provided by (used in) investing activities	(11,946,000)	39,975,000	(39,301,000)
Financing activities
Proceeds from term loan	10,000,000	0	0
Proceeds from Long-term Lines of Credit	6,838,000	0	0
Proceeds from issuance of common stock, net of commissions	0	20,226,000	0
Proceeds from 2019 Notes issuance	0	0	55,000,000
Repayment of long-term debt	(501,000)	0	(51,826,000)
Payments of debt and equity issuance costs	(79,000)	(684,000)	(1,888,000)
Proceeds from exercise of stock options	209,000	451,000	1,058,000
Proceeds from stock issuance from ESPP	1,285,000	1,323,000	1,075,000
Payments for taxes related to net share settlement of equity awards and other	(1,793,000)	(459,000)	(629,000)
Net cash provided by financing activities	15,959,000	20,857,000	2,790,000
Effect of foreign exchange rate fluctuations on cash and cash equivalents	(21,000)	385,000	56,000
Net increase (decrease) in cash, cash equivalents and restricted cash	(40,069,000)	45,800,000	(71,665,000)
Cash and cash equivalents and restricted cash at beginning of period	69,536,000	23,736,000	95,401,000
Cash and cash equivalents and restricted cash at end of period	29,467,000	69,536,000	23,736,000
Supplemental disclosures of cash flow information
Cash paid for interest	3,149,000	3,089,000	3,542,000
Cash paid for income taxes, net of refunds	2,085,000	521,000	205,000
Non-cash right-of-use assets and lease liabilities	(2,435,000)	36,225,000	10,402,000
Unpaid debt and equity issuance costs	0	0	534,000
Asset retirement obligations	$ 710,000	$ 325,000	$ 312,000