Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating activities
Net loss	$ (94,820)	$ (90,879)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation	11,404	13,669
Lease incentives received or receivable	3,861	0
Amortization of right-of-use lease assets	3,713	3,601
Depreciation	3,510	2,431
Long-lived asset impairment	1,900	0
Accretion of debt issuance costs	148	165
Amortization of premium (accretion of discount) on short-term investments	(1,118)	676
Loss on disposal of property and equipment	0	60
Changes in operating assets and liabilities:
Accounts receivable	348	(913)
Inventory, net	(3,537)	(13,487)
Prepaid expenses and other current assets	507	604
Other noncurrent assets	2	(892)
Accounts payable	267	(1,168)
Accrued expenses	1,554	79
Other current liabilities	432	81
Lease liabilities	(1,866)	(1,208)
Other noncurrent liabilities	48	87
Net cash used in operating activities	(73,647)	(87,094)
Investing activities
Purchases of short-term investments	(183,595)	(174,713)
Maturities of shot-term investments	178,035	119,647
Sales of short-term investments	20,337	21,522
Purchases of property and equipment	(970)	(6,022)
Net cash provided (used) by investing activities	13,807	(39,566)
Financing activities
Proceeds from issuance of common stock under employee stock purchase plan	702	1,180
Proceeds from issuance of common stock under equity incentive plans	13	171
Repurchases of common stock under equity incentive plans	(19)	(450)
Net cash provided by financing activities	696	901
Net decrease in cash and cash equivalents and restricted cash	(59,144)	(125,759)
Cash and cash equivalents and restricted cash, beginning of year	75,977	201,736
Cash and cash equivalents and restricted cash, end of period	16,833	75,977
Supplemental disclosure for cash activities
Interest paid	941	561
Supplemental disclosure for non-cash activities
Lease liability recognized upon lease modifications during the period	19,475	0
Inventory transferred to property and equipment	7,643	104
Purchases of inventory included in accounts payable	1,116	1,601
Vesting of common stock issued for early exercise of stock options	394	705
Purchase of property plant and equipment included in accounts payable	24	318
Purchases of inventory included in accrued expenses	168	226
Initial lease liability recognized upon lease commencements during the period	0	43,231
Initial lease liability recognized upon adoption of ASC 842	0	7,074
Reduction of lease liability for lease termination	0	334
Noncurrent deposit transferred to property and equipment	$ 0	$ 759