Refers to the annual percent of decline in premium prepayments.

No definition available.

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Namespace Prefix:	metc_
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Balance Type:	na
Period Type:	duration

- Definition

Annual percentage of premium prepayment.

+ References

No definition available.

+ Details

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Namespace Prefix:	metc_
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Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of monthly installments under a debt agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	metc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Refers to the number of employees furloughed.

+ References

No definition available.

+ Details

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Data Type:	xbrli:decimalItemType
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- Definition

Represents the number of major customers accounting for 10% or more of the specified concentration risk benchmark, which includes, but not limited to, sales revenue, accounts receivable, etc.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of installments.

+ References

No definition available.

+ Details

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Namespace Prefix:	metc_
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Balance Type:	na
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- Definition

Refers to the percent of salary reduction.

+ References

No definition available.

+ Details

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Namespace Prefix:	metc_
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Balance Type:	na
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- Definition

Percentage of furloughed employees recalled.

+ References

No definition available.

+ Details

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Face (par) amount of debt instrument at time of issuance.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Balance Type:	na
Period Type:	instant

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
-Paragraph 14
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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Note 11 - Subsequent Events (Details) $ in Millions			1 Months Ended			3 Months Ended
Note 11 - Subsequent Events (Details) $ in Millions	Apr. 20, 2020 USD ($)	Apr. 16, 2020 USD ($)	Mar. 31, 2020	Feb. 29, 2020	Jan. 31, 2020	Mar. 31, 2020 customer	Mar. 31, 2019	Apr. 01, 2020 employee
Subsequent Events
Percentage of furloughed workforce recalled	0.33%
Subsequent Event
Subsequent Events
Furloughed employees \| employee								182
Percentage salaries were reduced								30.00%
PPP Loan \| Subsequent Event
Subsequent Events
Proceeds from loan \| $	$ 8.4
Debt Instrument, Interest Rate, Stated Percentage	1.00%
KeyBank National Association \| Equipment Loan \| Subsequent Event
Subsequent Events
Debt Instrument, Interest Rate, Stated Percentage		7.45%
Debt Instrument, Face Amount \| $		$ 4.7
Number Of Monthly Installments		36 months
Debt Instrument, Monthly Installment, Amount \| $		$ 147.0
Annual percent of premium prepayment		3.00%
Annual premium decline in premium prepayment		1.00%
Revenue Benchmark \| Customer Concentration Risk
Subsequent Events
Number of Major Customers \| customer						3
Concentration Risk, Percentage			16.00%	18.00%	39.00%	73.00%	55.00%
Revenue Benchmark \| Contractual obligations for purchases
Subsequent Events
Number of Major Customers \| customer						2
Concentration Risk, Percentage						56.00%
Accounts Receivable. \| Customer Concentration Risk
Subsequent Events
Number of Major Customers \| customer						3
Concentration Risk, Percentage						69.00%