Redeemable Convertible Preferred Stock, Redeemable Common Stock, and Stockholders Equity (Deficit) - Warrants to Purchase Common Stock (Q2) (Details) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2024 |
Mar. 21, 2025 |
Dec. 31, 2024 |
|
| Equity [Abstract] | |||||
| Warrant liability | $ 200 | ||||
| Change in fair value loss | $ 49 | $ 64 | |||
| Exercise price of warrants (usd per share) | $ 1.5495 | ||||
| Fair value adjustment of warrants, before modification | $ 29 | ||||
| Modification fees | $ 2 | ||||