REVENUE FROM CONTRACTS WITH CUSTOMERS - Narrative (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Jun. 30, 2024 |
Jun. 30, 2023 |
Jun. 30, 2024 |
Jun. 30, 2023 |
Sep. 30, 2023 |
|
| Revenue from Contract with Customer [Abstract] | |||||
| Revenue from performance contracts | $ 294.4 | $ 883.3 | $ 880.4 | $ 316.2 | |
| Performance bonuses recognized | 11.8 | $ 11.4 | 37.4 | $ 33.0 | |
| Capitalized fulfillment costs | $ 11.6 | $ 11.6 | $ 11.4 | ||