Commitments and Contingencies (Details) - USD ($) $ in Millions |
6 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Jun. 05, 2026 |
Jun. 30, 2026 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Long-term Purchase Commitment [Line Items] | ||||
| Returned deposit related to terminated acquisition | $ 0.0 | $ 29.0 | ||
| Arbitration Relating to Terminated Anglo American Acquisition | ||||
| Long-term Purchase Commitment [Line Items] | ||||
| Returned deposit related to terminated acquisition | $ 29.0 | |||
| Other Payments to Acquire Businesses | $ 75.0 | |||
| Other Payments To Acquire Businesses, Outstanding | 46.0 | |||
| Loss Contingency, Damages Sought, Value | $ 755.0 | |||
| Arbitration Relating to Terminated Anglo American Acquisition | Asset Value Diminution | ||||
| Long-term Purchase Commitment [Line Items] | ||||
| Loss Contingency, Damages Sought, Value | $ 628.4 | |||
| Capital Addition Purchase Commitments | ||||
| Long-term Purchase Commitment [Line Items] | ||||
| Unrecorded unconditional purchase obligation (within next 12 months) | $ 37.3 | |||