Derivative Financial Instruments - Narrative (Details) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Sep. 30, 2024 |
Sep. 30, 2023 |
Sep. 30, 2022 |
|
| Derivatives, Fair Value [Line Items] | |||
| Derivative, notional amount | $ 0 | $ 0 | |
| Deferred gains (losses) in comprehensive loss related to foreign exchange hedging | 0 | 0 | |
| Other comprehensive gain (loss), cash flow hedge, loss, after reclassification and tax | (1,000,000) | (12,000,000) | $ 30,000,000 |
| Interest Rate Swap | |||
| Derivatives, Fair Value [Line Items] | |||
| Derivative, notional amount | 0 | 500,000,000 | |
| Other comprehensive gain (loss), cash flow hedge, loss, after reclassification and tax | 0 | 1,000,000 | |
| Pre-tax gains (losses) of the company derivative interest rate swaps | (1,000,000) | (16,000,000) | |
| Foreign Exchange Forward | |||
| Derivatives, Fair Value [Line Items] | |||
| Losses on derivative, net | $ 1,000,000 | $ 6,000,000 | |