BASIS OF PRESENTATION (Policies)	3 Months Ended
BASIS OF PRESENTATION (Policies)	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying Unaudited Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States (“GAAP”) for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results that may be expected for future periods. The Consolidated Balance Sheet at December 31, 2017 has been derived from the Audited Consolidated Financial Statements at that date but does not include all disclosures required by GAAP. This Form 10-Q report should be read in conjunction with CONSOL Energy Inc.'s Annual Report on Form 10-K for the year ended December 31, 2017, which includes all disclosures required by GAAP.
Basis of Consolidation	Basis of Consolidation The Unaudited Consolidated Financial Statements include the accounts of CONSOL Energy Inc., and its wholly owned and majority-owned and/or controlled subsidiaries. The portion of these entities that is not owned by the Company is presented as non-controlling interest. All significant intercompany transactions and accounts between subsidiaries within the Company have been eliminated in consolidation. Prior to the separation and distribution, CONSOL Energy did not operate as a separate, standalone entity. The Company's operations were included in ParentCo's financial results. Accordingly, for all periods prior to the separation and distribution, the accompanying Unaudited Consolidated Financial Statements were prepared from ParentCo's historical accounting records and were presented on a standalone basis as if the Company's operations had been conducted independently from ParentCo. Such Unaudited Consolidated Financial Statements include the historical operations that were considered to comprise the Company's businesses, as well as certain assets and liabilities that were historically held at ParentCo's corporate level but were specifically identifiable or otherwise attributable to the Company. ParentCo's net investment in these operations is reflected as Parent Net Investment in the accompanying Unaudited Consolidated Financial Statements. All significant intercompany transactions between ParentCo and the Company were included within Parent Net Investment in the accompanying Unaudited Consolidated Financial Statements.
Cost Allocations	Cost Allocations The description and information on cost allocations is applicable for all periods included in the Unaudited Consolidated Financial Statements prior to the separation and distribution. Prior to the completion of the separation and distribution, the Company utilized centralized functions of ParentCo to support its operations, and in return, ParentCo allocated certain of its expenses to the Company. Such expenses represent costs related, but not limited, to treasury, legal, accounting, insurance, information technology, payroll administration, human resources, incentive plans and other services. These costs, together with an allocation of ParentCo overhead costs, are included within the Selling, General and Administrative Costs caption of the Unaudited Consolidated Statements of Income. Where it was possible to specifically attribute such expenses to activities of the Company, amounts have been charged or credited directly to the Company without allocation or apportionment. Allocation of all other such expenses was based on a reasonable reflection of the utilization of service provided or benefits received by the Company during the periods presented on a consistent basis, such as a percentage of total revenue and a percentage of total projected capital expenditures. The Company's management supports the methods used in allocating expenses and believes these methods to be reasonable estimates. Nevertheless, the Unaudited Consolidated Financial Statements of CONSOL Energy Inc. may not reflect the actual expenses that would have been incurred and may not reflect CONSOL Energy Inc.'s consolidated results of operations, financial position and cash flows had it been a standalone company during the periods prior to the separation and distribution. Actual costs that would have been incurred if CONSOL Energy Inc. had been a standalone company would depend on multiple factors, including organizational structure, capital structure, and strategic decisions made in various areas, including information technology and infrastructure. Transactions between CONSOL Energy Inc. and ParentCo were included as related party transactions in the Unaudited Consolidated Financial Statements and were considered to be effectively settled for cash at the time the transaction was recorded. The total net effect of the settlement of these transactions is reflected in the accompanying Unaudited Consolidated Statements of Cash Flows as a financing activity and in the Unaudited Consolidated Balance Sheets as Parent Net Investment. Long-term employee obligations, comprised of pensions, OPEB, CWP and workers' compensation, have been allocated to CONSOL Energy Inc. on the basis of the underlying employees comprising those plans. All external debt not directly attributable to the ParentCo Coal Business has been excluded from the Unaudited Consolidated Balance Sheets of CONSOL Energy Inc.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-02 - Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, which allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the newly enacted federal corporate income tax rate under the Tax Cuts and Jobs Act. The amount of the reclassification would be the difference between the historical corporate income tax rate and the newly enacted 21% corporate income tax rate. The ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and should be applied prospectively to an award modified on or after the adoption date. Early adoption is permitted. CONSOL Energy adopted the new guidance during the three months ended March 31, 2018 and elected to make the reclassification. As a result, retained earnings increased $84,727 with a corresponding decrease to accumulated other comprehensive income. In January 2018, the FASB issued ASU 2018-01 - Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842. This Update, if elected, would not require an entity to reassess the accounting treatment of existing land easements not currently accounted for as a lease under Topic 840. Once an entity adopts Topic 842, it should apply that Topic prospectively to all new (or modified) land easements to determine whether the arrangement should be accounted for as a lease. For public business entities, the amendments in this update are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application of the amendments in this update is permitted for all entities. Management is currently evaluating the impact this guidance may have on the Company’s financial statements. In November 2016, the FASB issued ASU 2016-18 - Statement of Cash Flows (Topic 230) - Restricted Cash, which addressed the diversity that exists in the classification and presentation of changes in restricted cash and restricted cash equivalents on the statement of cash flows. The amendments in this Update require that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The amendments in the Update are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. This guidance was adopted during the three months ended March 31, 2018, and there was no material impact on the Company's consolidated financial statements. In February 2016, the FASB issued ASU 2016-02 - Leases (Topic 842), which increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. Update 2016-02 does retain a distinction between finance leases and operating leases, which is substantially similar to the classification criteria for distinguishing between capital leases and operating leases in the previous lease guidance. Retaining this distinction allows the recognition, measurement and presentation of expenses and cash flows arising from a lease to not significantly change from previous GAAP. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities, but to recognize lease expense on a straight-line basis over the lease term. For both financing and operating leases, the right-to-use asset and lease liability will be initially measured at the present value of the lease payments in the statement of financial position. The accounting applied by a lessor is largely unchanged from that applied under previous GAAP. For public business entities, the amendments in this Update are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. Management is currently evaluating the impact this guidance may have on the Company’s financial statements.
Earnings per Share	Earnings per Share Basic earnings per share are computed by dividing net income attributable to CONSOL Energy Shareholders by the weighted average shares outstanding during the reporting period. Dilutive earnings per share are computed similarly to basic earnings per share, except that the weighted average shares outstanding are increased to include additional shares from restricted stock units and performance share units, if dilutive. The number of additional shares is calculated by assuming that outstanding restricted stock units and performance share units were released, and that the proceeds from such activities were used to acquire shares of common stock at the average market price during the reporting period.