Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net loss	$ (115,254,000)	$ (110,078,000)	$ (40,696,000)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	5,871,000	5,738,000	4,919,000
Stock-based compensation expense	30,173,000	19,374,000	17,458,000
Non-cash operating lease cost	3,450,000	3,238,000	2,831,000
Payment of accrued interest on long-term debt	0	(2,593,000)	0
Gain on sale of business	0	0	(49,922,000)
Loss (gain) on equity securities	0	300,000	(625,000)
Loss on extinguishment of long-term debt	0	7,143,000	0
Amortization of premium and accretion of discount on short-term investments, net	(1,765,000)	(121,000)	(204,000)
Amortization of deferred financing costs	1,429,000	8,881,000	810,000
Conversion of accrued interest to long-term debt	0	0	2,193,000
Loss on disposal of property and equipment	5,000	119,000	1,152,000
Provision for inventory obsolescence and bad debt	2,040,000	886,000	869,000
Changes in operating assets and liabilities
Accounts receivable	(9,526,000)	(3,949,000)	(9,805,000)
Inventory	(10,520,000)	(4,909,000)	(8,475,000)
Prepaid expenses and other assets	(5,443,000)	4,321,000	(3,350,000)
Accounts payable	8,687,000	(3,170,000)	(599,000)
Accrued liabilities	(914,000)	(21,000)	1,276,000
Accrued compensation and other employee benefits	2,497,000	(936,000)	3,567,000
Cash payments received from customers	(353,000)	(4,758,000)	(1,778,000)
Deferred revenue and other liabilities	3,336,000	2,033,000	(6,536,000)
Operating lease liabilities	(4,262,000)	(3,160,000)	(2,506,000)
Net cash used in operating activities	(90,549,000)	(81,662,000)	(89,421,000)
Investing activities
Purchases of property and equipment	(6,348,000)	(7,457,000)	(7,885,000)
Purchase of internal-use software assets	(2,299,000)	0	0
Proceeds from sale of business	0	0	40,000,000
Proceeds from sale of short-term investments	4,000,000	21,218,000	2,500,000
Proceeds from maturity of short-term investments	44,664,000	116,284,000	97,970,000
Purchases of short-term investments	(260,239,000)	(38,804,000)	(147,744,000)
Net cash (used in) provided by investing activities	(220,222,000)	91,241,000	(15,159,000)
Financing activities
Proceeds from long-term debt	0	230,000,000	20,000,000
Deferred costs related to long-term debt	0	7,403,000	100,000
Repayment of long-term debt	0	(80,000,000)	0
Fees paid upon extinguishment of debt	0	(4,845,000)	0
Proceeds from sale of common stock, net	0	215,765,000	68,273,000
Proceeds from issuance of common stock warrants	0	737,000	2,228,000
Proceeds from issuance of common stock for employee stock purchase plan	2,427,000	2,190,000	1,952,000
Tax withholdings related to net share settlements of restricted stock units	(2,585,000)	(2,012,000)	(1,474,000)
Proceeds from exercise of stock options	6,452,000	18,751,000	18,387,000
Repayment of finance lease obligations	(236,000)	(135,000)	0
Net cash provided by financing activities	6,058,000	373,048,000	109,266,000
Effect of exchange rate changes on cash and cash equivalents	(67,000)	188,000	(9,000)
Net (decrease) increase in cash and cash equivalents	(304,780,000)	382,815,000	4,677,000
Cash and cash equivalents
Beginning of year	411,848,000	29,033,000	24,356,000
End of year	107,068,000	411,848,000	29,033,000
Supplemental disclosures
Cash paid for interest	6,038,000	4,571,000	5,683,000
Fair value of warrants issued with long-term debt	0	0	968,000
Cash paid for taxes	189,000	357,000	265,000
Instruments reclassified from inventory to property and equipment	525,000	854,000	605,000
Right-of-use assets obtained in exchange for finance lease liabilities	448,000	524,000	0
Right-of-use assets obtained in exchange for operating lease liabilities	929,000	0	28,060,000
Common stock received for sale of a business	$ 0	$ 0	$ 9,893,000