Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities:
Net loss	$ (63,888)	$ (52,614)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	10,915	11,486
Depreciation and amortization	721	739
Amortization of debt discount		502
Amortization of debt issuance costs	50
Amortization of premium on short-term investments	104	48
Impairment of property and equipment	47	80
Loss on disposal of property and equipment	96
Change in operating assets and liabilities:
Accounts receivable	(5,604)	3,325
Inventory	(8,088)	(724)
Prepaid expenses and other assets	(405)	(2,718)
Accounts payable	4,423	1,164
Accrued clinical and manufacturing liabilities	13,561	4,257
Accrued payroll and employee liabilities	(3,049)	(3,968)
Other accrued and other non-current liabilities	7,178	(3,515)
Net cash used in operating activities	(43,939)	(41,938)
Investing activities:
Purchases of short-term investments	(38,023)	(44,058)
Maturities and sales of short-term investments	49,957	40,500
Purchases of property and equipment	(1,044)	(786)
Proceeds from the sale of property and equipment	56
Net cash provided by (used in) investing activities	10,946	(4,344)
Financing activities:
Net proceeds from issuance of common stock under equity incentive plan	(637)	883
Net cash (used in) provided by financing activities	(637)	883
Net decrease in cash and cash equivalents	(33,630)	(45,399)
Cash and cash equivalents at beginning of year	90,541	105,138
Cash and cash equivalents at end of period	$ 56,911	$ 59,739