Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating activities
Net loss	$ (62,007)	$ (113,012)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	4,351	5,368
Depreciation and amortization	770	8,830
Non-cash lease expense	4,304	2,771
Impairment of long-lived assets	2,766	3,593
Changes in operating assets and liabilities:
Accounts receivable	259	(125)
Prepaid expenses and other current assets	1,879	604
Other long-term assets	0	741
Accounts payable	(2,429)	(1,194)
Accrued expenses and other liabilities	(3,133)	(7,712)
Net cash used in operating activities	(53,240)	(100,136)
Investing activities
Purchase of property and equipment, net	(486)	(1,615)
Net cash used in investing activities	(486)	(1,615)
Financing activities
Proceeds from stock option exercises	0	98
Proceeds from stock issuances pursuant to employee stock purchase plan	33	308
Net cash provided by financing activities	33	406
Net (decrease) increase in cash, cash equivalents and restricted cash	(53,693)	(101,345)
Cash, cash equivalents and restricted cash at beginning of year	131,967	233,312
Cash, cash equivalent and restricted cash at end of year	78,274	131,967
Supplemental disclosure of noncash activities
Right-of-use assets obtained in exchange for operating lease liabilities	7,265	19,245
Remeasurement of operating lease right-of-use asset for lease modification	$ (18,696)	$ 0