SEGMENT REPORTING - Reportable Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Revenues		$ 8,918	$ 3,066	$ 24,483	$ 10,655
Cost of revenues		2,741	1,189	5,670	3,299
Operating and other expenses
Research and development		56,371	54,043	170,484	146,152
General and administrative	[1]	30,380	20,834	86,241	57,399
Net loss		(437,214)	(75,064)	(595,909)	(199,203)
Development and Manufacturing Electric Aircrafts
Segment Reporting Information [Line Items]
Revenues		8,918	3,066	24,483	10,655
Cost of revenues		2,741	1,189	5,670	3,299
Operating and other expenses
Research and development		56,371	54,043	170,484	146,152
General and administrative		30,380	20,834	86,241	57,399
Other segment items		356,640	2,064	357,997	3,008
Net loss		$ (437,214)	$ (75,064)	$ (595,909)	$ (199,203)

[1] Includes related party amounts of $0 and $(549) (general and administrative) for the three months ended September 30, 2025 and 2024, respectively. Includes related party amounts of $(140) and $(1,057) (general and administrative) for the nine months ended September 30, 2025 and 2024, respectively (see Note 14). See accompanying notes to consolidated financial statements