Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating activities
Net loss	$ (26,865)	$ (5,141)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	5,919	2,836
Gain on disposal of property and equipment	0	(23)
Stock-based compensation	9,354	6,965
Amortization of debt issuance costs	0	83
Interest on end-of-term debt obligation	162	174
Write-down of excess supplies	1,088	0
Noncash lease expense	714	810
Revaluation of acquisition-related contingent consideration	332	0
Effect of foreign currency on operations	(17)	0
Changes in operating assets and liabilities:
Accounts receivable	1,742	(10,445)
Supplies	1,262	(3,206)
Prepaid expenses and other current assets	(923)	185
Other assets	134	(142)
Operating lease liability	(1,040)	(881)
Accounts payable	(534)	2,505
Accrued liabilities	(3,300)	1,258
Net cash used in operating activities	(11,972)	(5,022)
Investing activities
Purchases of property and equipment	(1,949)	(1,656)
Purchase of equity securities	(1,000)	0
Proceeds from disposal of property and equipment	0	23
Net cash used in investing activities	(2,949)	(1,633)
Financing activities
Proceeds from the issuance of common stock in a public offering, net	193,831	137,848
Payment of long-term debt	(100)	(24,900)
Payment of finance lease liability	0	(229)
Payment of taxes on vested restricted stock units	(3,161)	(810)
Proceeds from the exercise of common stock options and employee stock purchases	10,114	12,413
Net cash provided by financing activities	200,684	124,322
Net increase in cash, cash equivalents and restricted cash	185,763	117,667
Cash, cash equivalents and restricted cash at beginning of period	159,920	78,598
Cash, cash equivalents and restricted cash at end of period	345,683	196,265
Supplementary cash flow information:
Purchases of property and equipment included in accounts payable and accrued liability	355	821
Interest paid on debt	3	330
Cash and cash equivalents	345,080
Restricted cash	603
Cash, cash equivalents and restricted cash at end of period	$ 345,683	$ 196,265