Note 7 - Credit Losses (Details Textual) - Other Non-trade Contractual Arrangements [Member] - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accounts Receivable, before Allowance for Credit Loss	$ 8,263	$ 8,263
Other Receivables [Member]
Allowance for Credit Loss, Receivable, Other, Current	12,436	12,329
Other Noncurrent Assets [Member]
Allowance for Credit Loss, Receivable, Other, Noncurrent	$ 3,457	$ 2,882

Amount of allowance for credit loss on receivable, classified as other and noncurrent.

No definition available.

Name:	ceix_AllowanceForCreditLossReceivableOtherNoncurrent
Namespace Prefix:	ceix_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_AccountsReceivableGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of allowance for credit loss on receivable, classified as other and current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(4))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_AllowanceForDoubtfulOtherReceivablesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=ceix_OtherNontradeContractualArrangementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=ceix_OtherReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: