Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities:
Net loss	$ (52,614)	$ (51,579)
Adjustments to reconcile net loss to net cash used for operating activities:
Stock-based compensation expense	11,486	11,974
Depreciation and amortization	739	621
Amortization of debt discount	502	310
Amortization of premium (accretion of discount) on short-term investments	48	(117)
Impairment of property and equipment	80	27
Change in operating assets and liabilities:
Accounts receivable	3,325	5,068
Prepaid expenses and other assets	(2,718)	10,803
Inventory	(724)	(9,881)
Accounts payable	1,164	8,804
Accrued clinical and manufacturing liabilities	4,257	707
Accrued payroll and employee liabilities	(3,968)	(6,478)
Other accrued liabilities	(3,515)	(3,194)
Net cash used for operating activities	(41,938)	(32,935)
Investing activities:
Purchases of short-term investments	(44,058)	(28,922)
Maturities and sales of short-term investments	40,500	95,675
Purchases of property and equipment	(786)	(2,938)
Net cash (used for) provided by investing activities	(4,344)	63,815
Financing activities:
Proceeds from issuance of common stock under equity incentive plan	883	504
Proceeds from warrant exercises		3
Net cash provided by financing activities	883	507
Net (decrease) increase in cash and cash equivalents	(45,399)	31,387
Cash and cash equivalents at beginning of year	105,138	71,898
Cash and cash equivalents at end of period	$ 59,739	$ 103,285