v3.24.4
Loan Payable (Q3) (Details)
3 Months Ended 9 Months Ended 12 Months Ended
Feb. 22, 2021
USD ($)
Sep. 30, 2024
USD ($)
Sep. 30, 2023
USD ($)
Sep. 30, 2024
USD ($)
Sep. 30, 2023
USD ($)
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Sep. 26, 2024
USD ($)
Jul. 12, 2024
payment
$ / shares
Term Loan                  
Short-term Debt [Line Items]                  
Initial borrowing capacity $ 40,000,000                
Interest rate (as percent) 12.00%                
Proceeds from issuance of convertible notes $ 25,000,000                
Amount no longer available for borrowing $ 15,000,000                
Debt term 2 years                
Unamortized debt discount $ 15,800,000                
Percentage of debt discount in excess of initial face value 63.00%                
Calculated effective interest rate 126.00% 28.20%   28.20%   28.20%      
Interest expense amortization   $ 0 $ 300,000 $ 45,700 $ 1,200,000 $ 1,400,000 $ 2,700,000    
Convertible promissory notes | Convertible Debt                  
Short-term Debt [Line Items]                  
Initial borrowing capacity               $ 2,300,000  
Interest rate (as percent)                 15.00%
Number of periodic payments | payment                 4
Debt instrument, convertible, conversion price (in dollars per share) | $ / shares                 $ 0.53
Debt instrument, prepayment penalty fee (as percent)                 10.00%
Default interest derivative   0   $ 0          
Mark-to-market adjustments of default interest derivative   $ 0