v3.24.4
Stockholders' Equity (Deficit) - January 2024 Securities Purchase Agreement (Q3) (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 15, 2024
Mar. 04, 2024
Jan. 12, 2024
Nov. 09, 2023
Oct. 02, 2023
Sep. 07, 2023
Feb. 27, 2023
Sep. 30, 2024
Sep. 30, 2024
Sep. 30, 2023
Dec. 31, 2023
Dec. 31, 2022
May 09, 2024
Jan. 11, 2024
Class of Stock [Line Items]                            
Number of warrants exercised on net basis (in shares)       2,904,269                    
Exercise price (in dollars per share)     $ 0.96 $ 2                    
Warrant term (years)   5 years 5 years         5 years 5 years   5 years      
Aggregate cost $ 2,800 $ 4,000 $ 4,000   $ 4,000 $ 5,000 $ 10,000              
Agent fees and other offering costs 300 500 400   400 400 700   $ 1,137 $ 1,135 $ 2,048 $ 0    
Proceeds from issuance of warrants $ 2,400 $ 3,500 $ 3,600 $ 6,500 $ 3,600 $ 4,600 $ 9,300              
Equity related to warrants               $ 2,443            
January Pre-Funded Warrants                            
Class of Stock [Line Items]                            
Number of warrants exercised on net basis (in shares)     2,787,000                      
Exercise price (in dollars per share)     $ 0.00001                      
January Warrants                            
Class of Stock [Line Items]                            
Number of warrants exercised on net basis (in shares)     3,687,000                      
Warrant term (years)     5 years                      
November Modified Warrants                            
Class of Stock [Line Items]                            
Number of warrants exercised on net basis (in shares)     5,808,538                      
Exercise price (in dollars per share)     $ 3.86                   $ 0.54  
Warrant term (years)     5 years                     4 years 9 months 29 days
Equity related to warrants     $ 1,200                      
Common Class A                            
Class of Stock [Line Items]                            
Number of shares sold (in shares)   1,320,000 900,000   290,000 210,000                
Purchase price (in dollars per share) $ 0.55 $ 0.87 $ 1.09   $ 2 $ 7.43                
Number of warrants exercised on net basis (in shares) 10,000,000                          
Exercise price (in dollars per share)               $ 575 $ 575   $ 575