Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities:
Net loss	$ (326,847)	$ (221,465)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	4,139	2,268
Stock-based compensation expense	60,452	35,412
Amortization of operating lease right-of-use assets	6,921	4,955
Net accretion of discounts on investments	(27,028)	(32,406)
Unrealized foreign exchange gains, net	(6,453)	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(2,530)	2,431
Operating lease right-of-use assets	(4,624)	0
Other assets	(22,052)	1,363
Accounts payable	3,275	4,746
Accrued compensation	1,174	5,745
Accrued manufacturing expenses	(54)	33,614
Accrued expenses	(26,334)	(511)
Operating lease liabilities	(1,265)	(4,132)
Net cash used in operating activities	(341,226)	(167,980)
Cash flows from investing activities:
Purchases of property and equipment	(18,406)	(10,808)
Purchases of investments	(2,271,486)	(1,126,286)
Purchases related to manufacturing facility and equipment construction-in-progress	(70,726)	0
Maturities of investments	869,688	368,919
Sales of investments	42,432	8,790
Net cash used in investing activities	(1,448,498)	(759,385)
Cash flows from financing activities:
Proceeds from exercise of common stock options	19,505	3,541
Proceeds from issuance of common stock related to at-the-market offerings, net of issuance costs	195,969	90,787
Proceeds from issuance of common stock from follow-on offerings, net of issuance costs	2,239,679	545,279
Release of restricted stock units	(13,207)	(3,546)
Proceeds from issuance of common stock under Employee Stock Purchase Plan	1,655	1,017
Net cash provided by financing activities	2,443,601	637,078
Effect of exchange rate changes on cash and cash equivalents	(924)	996
Net increase (decrease) in cash, cash equivalents and restricted cash	652,953	(289,291)
Cash, cash equivalents and restricted cash, beginning of period	398,554	835,528
Cash, cash equivalents and restricted cash, end of period	1,051,507	546,237
Supplemental disclosure of non-cash investing activities:
Purchases of property and equipment recorded in accounts payable and accrued expenses	$ 5,529	$ 433