Organization and Operations (Details) $ / shares in Units, $ in Millions |
9 Months Ended | ||
|---|---|---|---|
|
May 15, 2026
USD ($)
$ / shares
shares
|
Jun. 30, 2026
segment
$ / shares
|
Sep. 30, 2025
$ / shares
|
|
| Organization, Consolidation and Presentation of Financial Statements [Abstract] | |||
| Number of operating segments | segment | 1 | ||
| Number of reportable segments | segment | 1 | ||
| Fluence Energy, LLC | |||
| Subsidiary or Equity Method Investee [Line Items] | |||
| Fluence Energy, LLC percentage owned | 77.54% | 77.55% | 71.81% |
| Class A common stock | |||
| Subsidiary or Equity Method Investee [Line Items] | |||
| Number of shares issued in transaction (in shares) | shares | 23,000,000 | ||
| Sale of stock, price (in usd per share) | $ 0.00001 | ||
| Consideration received on transaction | $ | $ 0.5 | ||
| Common stock, par value (in usd per share) | $ 0.00001 | $ 0.00001 | |
| Class B-1 common stock | |||
| Subsidiary or Equity Method Investee [Line Items] | |||
| Number of shares issued in transaction (in shares) | shares | 10,066,414 | ||
| Common stock, par value (in usd per share) | $ 0.00001 | $ 0.00001 | $ 0.00001 |