Summary of Significant Accounting Policies - Liquidity Matters (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024
Policies
Net loss	$ 59,912	$ 87,544	$ 211,972	$ 255,418
Accumulated deficit	2,987,994		2,987,994		$ 2,776,022
Cash, cash equivalents and restricted cash	1,097,195	$ 1,041,438	1,097,195	$ 1,041,438	1,076,140	$ 945,587
Outstanding balance	80,295		80,295		$ 80,323
Collateral amount	150,000		150,000
Remaining borrowing capacity	20,000		20,000
UBS Credit Line
Policies
Outstanding balance	$ 80,300		$ 80,300