v3.24.2
STOCK BASED COMPENSATION (Q1) (Details) - USD ($)
3 Months Ended 12 Months Ended
Mar. 25, 2024
Mar. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Stock Based Compensations [Abstract]        
Number of shares issued under share-based payment arrangement (in shares)     0 0
Aggregate principal amount   $ 98,258,000 $ 40,700,000  
Vendor Convertible Notes [Member]        
Stock Based Compensations [Abstract]        
Aggregate principal amount   $ 7,500,000    
Maturity date   Mar. 31, 2027    
Interest rate   0.00%    
Convertible notes converted into shares of common stock (in shares)   10    
Vendor Convertible Notes [Member] | Research and Development Expense [Member]        
Stock Based Compensations [Abstract]        
Share based compensation expense   $ 30,142,500    
Executive Promissory Notes [Member]        
Stock Based Compensations [Abstract]        
Aggregate principal amount   $ 10,900,000    
Maturity date   Sep. 30, 2024    
Interest rate   0.00%    
Debt instrument, convertible, conversion price (in dollars per share)   $ 10    
Convertible notes converted into shares of common stock (in shares) 1,090,000      
Executive Promissory Notes [Member] | General and Administration Expense [Member]        
Stock Based Compensations [Abstract]        
Share based compensation expense   $ 54,445,500    
2024 Equity Incentive Plan [Member] | Digital World Acquisition Corp [Member]        
Stock Based Compensations [Abstract]        
Common stock, available for issuance (in shares)   13,252,544    
Number of shares issued under share-based payment arrangement (in shares)   0