Prepaids and Other Current Assets (FY) (Details) - USD ($) $ in Thousands |
Sep. 30, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
|---|---|---|---|
| Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] | |||
| Prepaid launch costs, current | $ 0 | $ 1,260 | $ 3,000 |
| Prepaid research and development | 1,655 | 2,415 | 2,841 |
| Prepaid insurance and other assets | 2,532 | 4,838 | 4,332 |
| Prepaids and other current assets | 4,187 | 8,513 | 10,173 |
| Non-current portion of prepaid launch costs | $ 1,000 | $ 400 | $ 4,400 |