Note 8 - Leases - Maturities of operating lease liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Weighted average remaining lease term, operating	5 years
Weighted average remaining lease term, financing	2 years
Weighted average discount rate, operating	6.00%
Weighted average discount rate, financing	4.20%
Maturities of financing lease liabilities
2023	$ 6,302
2024	4,005
2025	1,032
Total undiscounted lease payments	11,339
Less: Amounts representing interest	(453)
Present value of lease obligations	10,886
Maturities of operating lease liabilities
2023	161
2024	161
2025	164
2026	168
2027	168
Total undiscounted lease payments	822
Less: Amounts representing interest	(115)
Present value of lease obligations	707
Maturities of lease liabilities
2023	6,463
2024	4,166
2025	1,196
2026	168
2027	168
Total	12,161
Less: Amounts representing interest	(568)
Present value of lease obligations	$ 11,593	$ 8,085

Refers to the amount lease liabilities, includes both operating and financing.

No definition available.

Name:	metc_LeaseLiabilities
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of lessee's undiscounted obligation for lease payment for lease to be paid in third fiscal year following current fiscal year.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of lessee's undiscounted obligation for lease payment for lease to be paid in next fiscal year following current fiscal year.

+ References

No definition available.

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payment for lease to be paid in five fiscal year following current fiscal year.

+ References

No definition available.

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payment for lease to be paid in four fiscal year following current fiscal year.

+ References

No definition available.

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payment for lease to be paid in second fiscal year following current fiscal year.

+ References

No definition available.

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payment for lease.

+ References

No definition available.

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments.

+ References

No definition available.

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- References

No definition available.

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- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

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-Publisher FASB
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- Definition

Amount of lessee's undiscounted obligation for lease payments for finance lease.

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Amount of lessee's undiscounted obligation for lease payment for finance lease to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lessee's undiscounted obligation for lease payment for finance lease to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lessee's undiscounted obligation for lease payment for finance lease to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for finance lease.

+ References

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Namespace Prefix:	us-gaap_
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- Definition

Weighted average discount rate for finance lease calculated at point in time.

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- Definition

Weighted average remaining lease term for finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

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- References

No definition available.

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- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease.

+ References

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- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating lease.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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Weighted average discount rate for operating lease calculated at point in time.

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Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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