RELATED PARTY TRANSACTIONS (Details) $ in Thousands		1 Months Ended		3 Months Ended		9 Months Ended
	Sep. 03, 2025 USD ($) member shares	Sep. 30, 2025 USD ($) shares	Jul. 31, 2025 USD ($) building	Sep. 30, 2025 USD ($) shares	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) shares	Sep. 30, 2024 USD ($)	Sep. 26, 2025 shares
Related Party Transaction [Line Items]
Number of buildings in leaseback | building			2
Proceeds from sale-leaseback transaction						$ 32,658	$ 0
Sale-leaseback term			29 years
Issuance of stock					$ 261		1,231
Loss on issuance of convertible preferred stock				$ 355,551	0	355,551	0
Warrants issued to purchase common stock (in shares) | shares								2,552,467
Research and development				56,371	$ 54,043	170,484	$ 146,152
Series C Preferred Stock
Related Party Transaction [Line Items]
Issuance of stock				203,361		206,241
Series C-1 Preferred Stock
Related Party Transaction [Line Items]
Issuance of stock				$ 724,278		$ 724,278
GE Aerospace | Series C-1 Preferred Stock
Related Party Transaction [Line Items]
Issuance of common stock (in shares) | shares		16,723,599
Issuance of stock		$ 300,000
Related Party
Related Party Transaction [Line Items]
Proceeds from sale-leaseback transaction			$ 32,658
Sale-leaseback term			29 years
Related Party | Series C Preferred Stock
Related Party Transaction [Line Items]
Issuance of common stock (in shares) | shares				5,397,160		5,388,801
Related Party | Series C-1 Preferred Stock
Related Party Transaction [Line Items]
Issuance of common stock (in shares) | shares				668,261		668,261
Related Party | GE Aerospace
Related Party Transaction [Line Items]
Issuance of stock	$ 300,000
Loss on issuance of convertible preferred stock				$ 215,585		$ 215,585
Number of board members added | member	1
Collaboration agreement term	10 years
Warrants issued to purchase common stock (in shares) | shares								2,552,467
Related Party | GE Aerospace | Series C-1 Preferred Stock
Related Party Transaction [Line Items]
Issuance of common stock (in shares) | shares	16,723,599
Related Party | GE Collaboration Agreement
Related Party Transaction [Line Items]
Research and development				$ 308		$ 308