WORKERS' COMPENSATION AND PNEUMOCONIOSIS - Workers' Comp (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2021
Reconciliation of changes in the workers' compensation liability
Beginning balance	$ 50,017	$ 53,206	$ 49,452	$ 53,448
Changes in accruals	2,196	2,271	6,070	4,546
Payments	(2,646)	(3,278)	(6,505)	(6,082)
Interest accretion	551	287	1,101	574
Valuation loss (gain)	990	(5,265)	990	(5,265)
Ending balance	51,108	$ 47,221	51,108	$ 47,221	$ 53,448
Estimated present value of future obligations and other information
Workers' compensation discount rate				4.22%	2.41%
Other long-term assets
Estimated present value of future obligations and other information
Receivables for traumatic injury claims	$ 4,100		$ 4,100

Represents the change in the liability for workers' compensation due to payments made during the period.

No definition available.

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- Definition

Represents the change in the liability for workers' compensation due to an adjustment for valuation gain or loss.

+ References

No definition available.

+ Details

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- Definition

Represents the change in the liability for workers' compensation due to additional amounts accrued during the period.

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

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- Definition

Amount recognized for the passage of time, typically for liabilities, that have been discounted to their net present values. Excludes accretion associated with asset retirement obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- References

No definition available.

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- Definition

Carrying amount due after one year of the balance sheet date (or one operating cycle, if longer) of amount due in settlement of a claim for reimbursement from an insurance company when the Company has suffered a loss covered under an insurance policy.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

Percent discount applied to worker's compensation reserve liability to reduce the reserve to present value.

+ References

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- Definition

Carrying value as of the balance sheet date of obligations and payables pertaining to claims incurred of a workers compensation nature.

+ References

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