INCOME TAXES - (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
Jun. 04, 2025	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
INCOME TAXES
Percentage of discrete benefit		21.30%	12.70%	20.00%	23.50%
Refundable tax credit rate, percentage	2.50%
Refundable tax credit		$ 2.7		$ 5.3

Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to discrete items.

No definition available.

Name:	metc_EffectiveIncomeTaxRateReconciliationDiscreteExpenseBenefitPercent
Namespace Prefix:	metc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration