v3.26.1
Summary of Significant Accounting Policies and Estimates - Non-controlling Interest (Details)
Mar. 31, 2026
Sep. 30, 2025
Fluence Energy, LLC    
Summary of Significant Accounting Policies and Estimates    
Controlling Interest Ownership 72.05% 71.81%
AES Grid Stability    
Summary of Significant Accounting Policies and Estimates    
Non-Controlling Interest Ownership (AES) 27.95% 28.19%