v3.25.2
Fair Value Measures and Disclosures - Balance Sheet Grouping (FY) (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Dec. 31, 2023
Assets, Fair Value Disclosure [Abstract]      
Financial assets   $ 0 $ 2,368
Total financial assets $ 579,430 114,716 512,605
Liabilities, Fair Value Disclosure [Abstract]      
Total financial liabilities 698 200,089 527,047
Level 1 | Money market funds | Cash and cash equivalents      
Assets, Fair Value Disclosure [Abstract]      
Financial assets 55,508 2,411 87,258
Level 1 | Money market funds | Restricted cash and cash equivalents, current      
Assets, Fair Value Disclosure [Abstract]      
Financial assets 518,199 24,185 42,940
Level 1 | Money market funds | Restricted cash and cash equivalents, non-current      
Assets, Fair Value Disclosure [Abstract]      
Financial assets 0 56,250 206,846
Level 2      
Liabilities, Fair Value Disclosure [Abstract]      
Power purchase agreements 271 0  
Level 2 | Prepaid Expenses and Other Current Assets      
Assets, Fair Value Disclosure [Abstract]      
Financial assets   0 2,368
Level 2 | Certificates of deposit      
Assets, Fair Value Disclosure [Abstract]      
Financial assets 0 29,308 171,734
Level 3      
Assets, Fair Value Disclosure [Abstract]      
Power purchase agreements 3,444 2,562 1,459
Liabilities, Fair Value Disclosure [Abstract]      
Bifurcated embedded derivative liabilities   0 386,469
Warrant liabilities 0 199,645 70,930
Series B tranche liability   0 69,648
Power purchase agreements $ 427 $ 444 $ 0