v3.24.4
Stockholders' Equity (Deficit) - Common Stock and Preferred Stock (Q3) (Details)
Aug. 22, 2023
$ / shares
shares
Sep. 30, 2024
$ / shares
shares
Dec. 31, 2023
$ / shares
shares
Dec. 31, 2022
$ / shares
shares
Class of Stock [Line Items]        
Shares of stock authorized (in shares) 274,312,500      
Preferred stock, number of shares authorized (in shares)   20,000,000 20,000,000 20,000,000
Preferred stock, par value (in dollars per share) | $ / shares   $ 0.00001 $ 0.00001 $ 0.00001
Common Class A        
Class of Stock [Line Items]        
Stock split ratio 0.02      
Common stock, number of shares authorized (in shares) 250,000,000 250,000,000 250,000,000 250,000,000
Common stock, par value (in dollars per share) | $ / shares $ 0.00001 $ 0.00001 $ 0.00001 $ 0.00001
Common Class B        
Class of Stock [Line Items]        
Common stock, number of shares authorized (in shares) 4,312,500 4,312,500 4,312,500 4,312,500
Common stock, par value (in dollars per share) | $ / shares $ 0.00001 $ 0.00001 $ 0.00001 $ 0.00001
Preferred Stock        
Class of Stock [Line Items]        
Preferred stock, number of shares authorized (in shares) 20,000,000      
Preferred stock, par value (in dollars per share) | $ / shares $ 0.00001