Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Operating activities
Net loss	$ (311,351)	$ (223,858)	$ (146,962)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	59,904	55,012	43,118
Impairment of long-lived assets	3,856	4,925	0
Depreciation and amortization	8,313	7,373	3,565
Premiums and discounts on available for sale marketable securities	(8,879)	(13,983)	(5,229)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(2,361)	(8,903)	(1,961)
Accounts receivable	0	15,000	(15,000)
Contract asset	947	2,815	(1,226)
Accounts payable	(1,974)	(307)	2,038
Accrued expenses and other current liabilities	7,387	4,180	3,180
Deferred revenue	20,789	(41,075)	(8,609)
Operating lease right-of-use assets	2,666	2,541	4,797
Operating lease liabilities	(5,042)	1,921	18,582
Other non-current assets	(7,164)	168	909
Other non-current liabilities	18	(310)	(28)
Net cash used in operating activities	(232,891)	(194,501)	(102,826)
Investing activities
Purchase of property and equipment, net	(1,449)	(12,838)	(34,480)
Purchase of marketable securities	(1,007,628)	(901,226)	(189,151)
Maturities of marketable securities	488,016	509,987	363,517
Net cash provided by (used in) investing activities	(521,061)	(404,077)	139,886
Financing activities
Issuance of common stock and accompanying pre-funded warrants from January 2024 public offering, net of issuance costs of $14.9 million	0	301,373	0
Proceeds from issuance of common stock through At-The Market Sales Agreement, net of issuance costs of $1.2 million	0	48,740	0
Issuance of common stock and accompanying pre-funded warrants from August 2024 public offering, net of issuance costs of $12.2 million	0	246,506	0
Issuance of common stock from December 2025 public offering, net of issuance costs of $36.2 million	656,230	0	0
Proceeds from stock option exercises	61,621	11,790	2,860
Issuance of common stock and accompanying pre-funded warrants from June 2025 public offering, net of issuance costs of $15.7 million	272,671	0	0
Proceeds from employee stock purchase plan	1,685	2,018	1,408
Payments on financing leases	(1,494)	(1,576)	(76)
Net cash provided by financing activities	990,713	608,851	4,192
Net increase (decrease) in cash, cash equivalents and restricted cash	236,761	10,273	41,252
Cash, cash equivalents and restricted cash at beginning of period	126,050	115,777	74,525
Cash, cash equivalents and restricted cash at end of period	362,811	126,050	115,777
Supplemental disclosure of cash flow activities
Right-of-use assets obtained in exchange for operating lease liabilities	0	0	48,833
Cash paid for interest	312	206	162
Supplemental disclosure of noncash investing and financing activities
Purchases of property and equipment through finance and lease liabilities	1,028	2,742	0
Property and equipment purchases included in accounts payable and accrued expenses	80	60	4,016
Cash and cash equivalents	357,011	120,256	109,966
Restricted cash	5,800	5,794	5,811
Total cash, cash equivalents, and restricted cash	$ 362,811	$ 126,050	$ 115,777