Workers' Compensation and Pneumoconiosis (Black Lung) Obligations (Narrative) (Details) - USD ($) $ in Millions |
12 Months Ended | |||
|---|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
May 01, 2024 |
|
| Workers' Compensation [Line Items] | ||||
| Incurred claims, premium expenses and administrative fees related to workers compensation | $ 43.9 | $ 40.2 | $ 35.0 | |
| Other Non-current Liabilities [Member] | ||||
| Workers' Compensation [Line Items] | ||||
| Workers' compensation liability | 38.5 | 34.4 | ||
| Workers' Compensation Insurance [Member] | ||||
| Workers' Compensation [Line Items] | ||||
| Workers' compensation insurance, claims per occurrence | 0.5 | |||
| Workers' compensation insurance, aggregate claims | $ 29.1 | |||
| Collateral deposit | 73.2 | |||
| Incurred claims, premium expenses and administrative fees related to workers compensation | 8.9 | 8.9 | $ 16.3 | |
| Workers' compensation liability | $ 43.1 | $ 39.1 | ||