SHAREHOLDERS' EQUITY, Preferred Stock Dividends (Details) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2026 |
Mar. 31, 2025 |
|
| Equity [Abstract] | ||||
| Total dividends declared | $ 2 | $ 2 | $ 3 | $ 3 |
| Dividends declared per preferred share (in usd per share) | $ 0 | $ 15.94 | $ 15.94 | $ 31.88 |
| Total dividends paid | $ 3 | $ 2 | $ 4 | $ 3 |
| Dividends paid per preferred share (in usd per share) | $ 15.94 | $ 15.94 | $ 31.88 | $ 31.88 |
| Preferred stock redemption value over carrying value | $ 2 | $ 2 | ||